A method for accelerating synthesis of silica aerogel using electron beam irradiation technology

Abstract

The application belongs to the technical field of silica aerogel preparation, and particularly relates to a method for accelerating synthesis of silica aerogel by using electron beam irradiation technology, which comprises the following steps: (1) configuration of a precursor: uniformly mixing an organic silicon source, water and an organic solvent in proportion under normal temperature and pressure in an air atmosphere to obtain the precursor; (2) hydrolysis of the precursor: hydrolyzing the precursor prepared in step (1) under electron beam irradiation conditions to obtain the hydrolyzed precursor; and (3) preparation of the aerogel: adding ammonia water to the hydrolyzed precursor in step (2) to adjust the pH value, uniformly mixing and then waiting for gelation, and drying to obtain the aerogel. The method has the beneficial effect that the precursor is hydrolyzed under electron beam irradiation conditions, and the dose, temperature and humidity of the electron beam irradiation are further controlled, so that the hydrolysis time is shortened, and thus the efficiency of synthesizing the silica aerogel is improved.

Description

A method for accelerating the synthesis of silica aerogel using electron beam irradiation technology Technical Field

[0001] This invention belongs to the field of silica aerogel preparation technology, specifically relating to a method for accelerating the synthesis of silica aerogel using electron beam irradiation technology. Background Technology

[0002] Silica aerogel is a lightweight, porous nanomaterial composed of nano-sized silica particles. Silica aerogel possesses extremely high porosity (80%–99.8%) and extremely high specific surface area (up to 1000 m²). 2 / g), extremely low density (<0.003g / cm³) 3 With its excellent thermal insulation properties (down to 0.01 W / (m·K)), it has broad application prospects in optical engineering, electronics, pharmaceutical carriers, pipelines and external wall insulation.

[0003] Currently, the chemical method is commonly used in industry to synthesize silica aerogels, which mainly involves three steps. First, using the sol-gel method, a silicon source is mixed with water, and under the action of a catalyst, hydrolysis and condensation occur to form a wet gel. Then, the wet gel undergoes an aging treatment, and finally, the solvent is removed by drying to obtain the silica aerogel. This method mainly has the following problems:

[0004] 1. The hydrolysis step takes a long time;

[0005] 2. Other materials may be introduced during the production process, causing secondary pollution. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for accelerating the synthesis of silica aerogel using electron beam irradiation technology.

[0007] This invention relates to a method for accelerating the synthesis of silica aerogel using electron beam irradiation technology, comprising the following steps:

[0008] (1) Configuration of precursor:

[0009] Under normal temperature and pressure, in an air atmosphere, an organosilicon source, water and organic solvent are mixed evenly in proportion to obtain a precursor;

[0010] (2) Hydrolysis of precursors:

[0011] The precursor obtained in step (1) was hydrolyzed under electron beam irradiation to obtain the hydrolyzed precursor.

[0012] (3) Preparation of aerogel:

[0013] Add ammonia to the precursor after hydrolysis in step (2) to adjust the pH value, mix evenly, let stand and wait for gelation, and dry to obtain aerogel.

[0014] Preferably, in step (1), the volume ratio of the organosilicon source, water and organic solvent is 1:0.3-0.5:1-1.5.

[0015] Preferably, in step (1), the organosilicon source is one of tetraethyl silicate or triethoxymethylsilane.

[0016] Preferably, in step (1), the organic solvent is one of ethanol.

[0017] Preferably, in step (2), the electron beam irradiation dose is 15kGy to 60kGy.

[0018] Preferably, in step (2), the temperature of the electron beam irradiation is 20℃~35℃.

[0019] Preferably, in step (2), the humidity of the electron beam irradiation is 40% to 90%.

[0020] Preferably, in step (2), the precursor is hydrolyzed for 0s to 1.5s under electron beam irradiation.

[0021] Preferably, in step (3), ammonia is added to adjust the pH value to 8-9; gel is formed after standing for 4-48 hours.

[0022] Preferably, in step (3), the drying method is atmospheric pressure drying, the drying temperature is 50℃~60℃, and the drying time is 12h~24h.

[0023] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0024] (1) In the method of accelerating the synthesis of silica aerogel by electron beam irradiation technology, the precursor is hydrolyzed under electron beam irradiation conditions, which shortens the hydrolysis time and thus improves the efficiency of silica aerogel synthesis.

[0025] (2) The method of accelerating the synthesis of silica aerogel by electron beam irradiation technology, by controlling the dose, temperature and humidity of electron beam irradiation, enables the precursor to be completely hydrolyzed in the shortest time, and has a promoting effect on the hydrolysis of the precursor in both acidic and neutral environments, thereby further improving the hydrolysis rate of the precursor.

[0026] (3) The method of accelerating the synthesis of silica aerogel by electron beam irradiation technology is simple to operate, has high synthesis efficiency, does not require the introduction of any external material system, avoids secondary pollution, and is suitable for large-scale industrial production of silica aerogel. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0028] Figure 1 is a flowchart of the preparation process of aerogel in this invention;

[0029] Figure 2 is a comparison of the gelation under different irradiation doses provided in Example 1;

[0030] Figure 3 is a physical image of the aerogel provided in Example 2. Detailed Implementation

[0031] To better understand the above-mentioned objectives, features and advantages of the present invention, the present invention will be further described below in conjunction with embodiments.

[0032] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0033] Example 1

[0034] A method for accelerating the synthesis of silica aerogel using electron beam irradiation technology includes the following steps:

[0035] (1) Configuration of precursor:

[0036] At room temperature and pressure, in an air atmosphere, 4 ml of tetraethyl silicate, 5 ml of ethanol, and 1.8 ml of water were measured with a pipette and mixed thoroughly to obtain the precursor, which had a pH of 7.

[0037] (2) Hydrolysis of precursors:

[0038] The precursor obtained in step (1) was divided into four equal parts and hydrolyzed for 1 second under electron beam irradiation to obtain the hydrolyzed precursor. The electron beam irradiation parameters were: doses of 0 kGy, 15 kGy, 30 kGy and 45 kGy, temperature of 23°C and humidity of 40%.

[0039] (3) Preparation of aerogel:

[0040] Add 10 μL of ammonia water to the precursor after hydrolysis in step (2), mix well, let stand and wait for gelation, and dry at 50°C and normal pressure for 24 h to obtain aerogel.

[0041] Example 2

[0042] A method for accelerating the synthesis of silica aerogel using electron beam irradiation technology includes the following steps:

[0043] (1) Configuration of precursor: y

[0044] At room temperature and pressure, in an air atmosphere, 4 ml of triethoxymethylsilane, 4 ml of ethanol, and 1.8 ml of water were measured with a pipette and mixed thoroughly to obtain the precursor, which had a pH of 7.

[0045] (2) Hydrolysis of precursors:

[0046] The precursor obtained in step (1) was divided into four equal parts and hydrolyzed for 1.5 s under electron beam irradiation to obtain the hydrolyzed precursor. The electron beam irradiation parameters were: doses of 0 kGy, 15 kGy, 30 kGy and 45 kGy, temperature of 23 °C and humidity of 40%.

[0047] (3) Preparation of aerogel:

[0048] Add 50 μL of ammonia water to the precursor after hydrolysis in step (2), mix well, let stand and wait for gelation, dry at 50°C and normal pressure for 24 h to obtain aerogel. The actual object is shown in Figure 3 (left is 30 kGy, right is 45 kGy).

[0049] Example 3

[0050] The difference between this embodiment and Embodiment 1 is that 10 μL of hydrochloric acid was added to the precursor, and the pH value of the precursor was 3; the volume of ammonia added was 100 μL.

[0051] Experimental Example 1,

[0052] Table 1. Results of gelation time in Examples 1-3

[0053]

[0054] Table 1 shows that in Example 1, the precursors exhibited different gelation times under different irradiation doses; the higher the irradiation dose, the shorter the gelation time. Precursors not treated with irradiation did not gel. In Example 2, the precursors under neutral conditions showed different gelation times under different irradiation doses; the higher the irradiation dose, the shorter the gelation time. In Example 3, the precursors under acidic conditions showed different gelation times under different irradiation doses; the higher the irradiation dose, the shorter the gelation time. Therefore, electron beam irradiation promotes the hydrolysis of precursors in both acidic and neutral environments.

[0055] Experimental Example 2,

[0056] The effect of different electron beam irradiation doses on the gelation condition was investigated in Example 1 when the gelation time was 4 hours. The results are shown in Figure 2.

[0057] As can be seen from Figure 2, the precursor in Example 1 exhibits different gelation behavior under different irradiation doses. The higher the irradiation dose received by the precursor, the more obvious the gelation behavior becomes, and the precursor that has not undergone irradiation treatment does not gel.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

[0059] The gelation time for Examples 1-3 was recorded, and the results are shown in Table 1.

Claims

1. A method for accelerating the synthesis of silica aerogel using electron beam irradiation technology, characterized in that, The process includes the following steps: (1) Preparation of the precursor: Under normal temperature and pressure, in an air atmosphere, the organosilicon source, water and organic solvent are mixed evenly in proportion to obtain the precursor; (2) Hydrolysis of the precursor: The precursor obtained in step (1) is hydrolyzed under electron beam irradiation to obtain the hydrolyzed precursor; (3) Preparation of the aerogel: Ammonia water is added to the hydrolyzed precursor in step (2) to adjust the pH value, and after mixing evenly, it is allowed to stand for gelation, and then dried to obtain the aerogel; In step (1), the volume ratio of the organosilicon source, water and organic solvent is 1:0.3~0.5:1~1.5; In step (1), the organosilicon source is tetraethyl or triethyl silicate. One of ethoxymethylsilanes; in step (1), the organic solvent is ethanol; in step (2), the electron beam irradiation dose is 15kGy to 60kGy; in step (2), the electron beam irradiation temperature is 20℃ to 35℃; in step (2), the electron beam irradiation humidity is 40% to 90%; in step (2), the precursor is hydrolyzed for 1s to 1.5s under electron beam irradiation conditions; in step (3), ammonia is added to adjust the pH value to 8 to 9; gel is formed after standing for 4h to 48h; in step (3), the drying method is atmospheric pressure drying, the drying temperature is 50℃ to 60℃, and the drying time is 12h to 24h.

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