Preparation method of carbon aerogel microspheres with controllable particle size

Abstract

The present invention discloses a method for preparing carbon aerogel microspheres with controllable particle size. Phenol is melted at a temperature of 45 - 60 °C to prepare liquid phenol - reaction solution A; sodium carboxymethylcellulose, melamine, and sodium hydroxide are dissolved in an aqueous formaldehyde solution to prepare a formaldehyde - dispersant - catalyst solution - reaction solution B; cetyltrimethylammonium bromide is stirred and dissolved in white oil to prepare reaction solution C; reaction solution A and reaction solution C are directly mixed, heated and stirred at a temperature of 75 - 95 °C, and reaction solution B is uniformly injected into the reactor by a peristaltic pump during the heating and stirring process to obtain a milky yellow suspension; the carbon aerogel microspheres are obtained by separation and drying. The present invention can accurately control the particle size of carbon aerogel microspheres by controlling the dosage and addition rate of sodium carboxymethylcellulose and cetyltrimethylammonium bromide, and can be practically applied to the fields of energy storage, adsorption separation, catalysis, sensors, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon aerogel material preparation, and particularly relates to a method for preparing carbon aerogel microspheres with controllable particle size. Background Art

[0002] Carbon aerogel is a new type of porous material with high specific surface area, low density, high porosity, excellent chemical stability and thermal stability. Due to its excellent pore structure and electrical conductivity, it is widely used in the fields of energy storage, adsorption separation, catalysis, polymer materials, magnetic materials, other nanomaterials and sensors, etc., and has broad application value in the fields of mechanics, acoustics, electricity, heat and optics. Different application fields have quite different performance requirements for carbon aerogel. For example, in the electromagnetic field, only carbon aerogel with low density and high conductivity can exhibit excellent multi-band and long-term effective electromagnetic interference performance. In this state, the carbon aerogel powder is mostly in a micro-nano structure; in the field of supercapacitors, in order to facilitate the production of supercapacitor electrode materials, it is mostly required that the particle size of the carbon aerogel powder is less than 10 microns. Thus, it can be seen that a suitable particle size distribution plays an important role in the application of carbon aerogel.

[0003] At present, the large-scale preparation method of carbon aerogel mostly adopts the path of first synthesizing a bulk gel and then grinding and crushing it. In this process, the solvent exchange and supercritical drying processes make the preparation process time-consuming and costly; and grinding will damage the surface state of the carbon aerogel, and agglomeration and bonding phenomena will be observed microscopically, ultimately limiting the commercial application of the material. Chinese Patent ZL201510648933.6 discloses a high-density activated carbon aerogel and its preparation method, which is characterized by adopting emulsion polymerization and atmospheric drying and other methods. Its preparation method is simple, with low cost, and the preparation and forming processes can be completed at one time. Its post-treatment is simple and convenient, which greatly saves time and energy consumption, making it more conducive to industrial application. However, this preparation method is in the laboratory research stage, and it is necessary to evacuate and then fill with inert gas protection at 150°C. The reaction conditions are harsh, and it needs to be heated to 600 - 800°C, with high energy consumption and high preparation cost, making it difficult to be applied in large-scale industrial production. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing carbon aerogel microspheres with controllable particle size in view of the technical problems existing in the prior art, such as long preparation process, high cost, small scale, easy agglomeration of products and difficulty in large-scale industrial production, so as to meet the needs of industrial production.

[0005] To achieve the above object of the present invention, a method for preparing carbon aerogel microspheres with controllable particle size of the present invention includes the following steps:

[0006] S1: Melt phenol at a temperature of 45 - 60 °C to form liquid phenol - reaction solution A.

[0007] S2: Dissolve sodium carboxymethylcellulose, melamine, and sodium hydroxide in an aqueous formaldehyde solution, and stir at a set temperature until clear and transparent to prepare a formaldehyde - dispersant - catalyst solution - reaction solution B; the mass concentration of the aqueous formaldehyde solution is 35 - 39%, the mass ratio of sodium carboxymethylcellulose to the aqueous formaldehyde solution is 1:50 - 80, the mass ratio of the aqueous formaldehyde solution to melamine is 1:0.01 - 0.1, and the molar ratio of the aqueous formaldehyde solution to sodium hydroxide is 1:0.01 - 0.02;

[0008] The stirring temperature is controlled at 30 - 60 °C, and the stirring rate is controlled at 15 - 30 rpm

[0009] S3: Stir and dissolve cetyltrimethylammonium bromide in white oil to prepare reaction solution C; the mass ratio of cetyltrimethylammonium bromide to white oil is 1:100 - 150;

[0010] In this step, the stirring and dissolving rate is controlled in the range of 150 - 200 r / min, and the stirring and dissolving time is 5 - 10 min.

[0011] S4: Directly mix reaction solution A and reaction solution C, heat and stir at a temperature of 75 - 95 °C, and uniformly inject reaction solution B into the reactor with a peristaltic pump during the heating and stirring process to obtain a milky - yellow suspension;

[0012] In this step, reaction solution B is added completely within 60 min, the stirring rate is controlled at 200 - 400 r / min, and the reaction time is controlled at 18 - 24 h; the volume ratio of reaction solution A to reaction solution C is controlled at 1:1 - 5.

[0013] As a preference of the present invention, the molar ratio of phenol in reaction solution A to formaldehyde in reaction solution B is controlled at 1:1.2 - 1.8.

[0014] S5: Perform solid - liquid separation on the milky - yellow suspension obtained in step S4, wash the separated solid product with one of ethanol, acetone, and dichloromethane multiple times, and dry the washed and separated solid product at 30 - 60 °C to obtain a carbon aerogel microsphere product.

[0015] The method of the present invention can respectively prepare carbon aerogel microsphere products with different particle sizes where D50 is between 25 - 100 microns, D50 is between 100 - 300 microns, and D50 is greater than 300 microns according to market demands. Taking the phenol dosage as 1 mol, the dosages of the remaining components are:

[0016] 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 2.0 - 2.5 g of sodium carboxymethyl cellulose, 3.2 - 4.0 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose is less than 2.0. The rotation speed of the peristaltic pump is 3 - 6 mL / min, and the particle size D50 of the prepared carbon aerogel microspheres is between 25 and 100 microns.

[0017] 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 2.2 - 3.0 g of sodium carboxymethyl cellulose, 3.0 - 3.8 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose is less than 1.7. The rotation speed of the peristaltic pump is 3 - 6 mL / min, and the particle size D50 of the prepared carbon aerogel microspheres is between 100 and 300 microns.

[0018] 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 3.2 - 4.0 g of sodium carboxymethyl cellulose, 2.5 - 3.0 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose is less than 1.0. The rotation speed of the peristaltic pump is 8 - 12 mL / min, and the particle size D50 of the prepared carbon aerogel microspheres is greater than 300 microns.

[0019] Compared with the prior art, the preparation method of the carbon aerogel microspheres with controllable particle size of the present invention has the following beneficial effects:

[0020] (1) The main raw materials selected, such as phenol and formaldehyde, have low cost, wide sources, mild reaction conditions, and simple process flow.

[0021] (2) The improved hydrothermal method has a high safety factor during the preparation process, and the particle size of the product can be accurately controlled by controlling the dosage and addition speed of sodium carboxymethyl cellulose and cetyltrimethylammonium bromide.

[0022] (3) Atmospheric drying effectively saves time and cost, which is beneficial to large-scale industrial production.

[0023] (4) According to market needs, carbon aerogel microsphere products with different particle sizes, with D50 between 25 and 100 microns, D50 between 100 and 300 microns, and D50 greater than 300 microns, can be respectively prepared by adjusting process parameters. Specific embodiments

[0024] To describe the present invention, a preparation method of carbon aerogel microspheres with controllable particle size according to the present invention will be further described in detail below with reference to embodiments. However, the present invention is not limited to the embodiments.

[0025] Example 1

[0026] First, prepare reaction solution A: Take 94 g of phenol after melting at 45°C. Then, prepare reaction solution B: Take 162.2 g of formaldehyde solution with a mass concentration of 37%, 2.7 g of sodium carboxymethyl cellulose, 12.61 g of melamine, and 2.1 g of sodium hydroxide in a 500 mL beaker, and stir magnetically at 60°C and 20 rpm for 30 min until clear and transparent. Prepare reaction solution C: Take 3.0 g of cetyltrimethylammonium bromide in 400 g of white oil, and stir at 200 rpm for 10 min at room temperature to form a uniformly dispersed emulsion. Mix reaction solution A and reaction solution C in a 1000 mL round-bottom flask, and add reaction solution B into the flask uniformly by a peristaltic pump at a rate of 5 mL / min. Stir mechanically at 80°C and 300 rpm for 20 h. Recover the solid product by suction filtration, and dry it overnight in a blast drying oven at 50°C to obtain carbon aerogel microspheres with a particle size distribution of D10 100.157, D50 240.145, and D90 376.513 microns.

[0027] Example 2

[0028] Take 2.2 g of sodium carboxymethyl cellulose and 3.8 g of cetyltrimethylammonium bromide. Under the same conditions as in Example 1, the particle size distribution of the dried carbon aerogel microspheres is D10 57.412, D50 110.247, and D90 182.645 microns.

[0029] Example 3

[0030] Take 2.1 g of sodium carboxymethyl cellulose and 4.0 g of cetyltrimethylammonium bromide. React the uniformly mixed solution at 85°C for 18 h. Under the same conditions as in Example 1, the particle size distribution of the dried carbon aerogel microspheres is D10 10.127, D50 25.781, and D90 31.542 microns.

[0031] Example 4

[0032] Take 2.2 g of sodium carboxymethyl cellulose and 3.9 g of cetyltrimethylammonium bromide. Under the same conditions as in Example 1, the particle size distribution of the dried carbon aerogel microspheres is D10 20.543, D50 43.781, and D90 61.426 microns.

[0033] Example 5

[0034] Take 3.2 g of sodium carboxymethyl cellulose and 2.7 g of cetyltrimethylammonium bromide. Reaction solution C is evenly added into the flask by a peristaltic pump at a rate of 10 mL / min. Other conditions are the same as in Example 1. The particle size distribution of the dried carbon aerogel microspheres is D10 423.541, D50 800.745, and D90 1210.687 microns.

[0035] Based on the above embodiments, the present invention also carried out a pilot-scale amplification test, and the test indexes obtained were almost the same as those of the above embodiments, indicating that the present invention has good reliability.

Claims

1. A method for preparing carbon aerogel microspheres with controllable particle size, characterized in that The following process is adopted: S1: Melt phenol at a temperature of 45 - 60 °C to make liquid phenol - reaction solution A; S2: Dissolve sodium carboxymethyl cellulose, melamine, and sodium hydroxide in an aqueous formaldehyde solution, stir at a set temperature until clear and transparent to prepare a formaldehyde - dispersant - catalyst solution - reaction solution B; the mass concentration of the aqueous formaldehyde solution is 35 - 39%, the mass ratio of sodium carboxymethyl cellulose to the aqueous formaldehyde solution is 1:50 - 80, the mass ratio of the aqueous formaldehyde solution to melamine is 1:0.01 - 0.1, and the molar ratio of the aqueous formaldehyde solution to sodium hydroxide is 1:0.01 - 0.02; S3: Stir and dissolve cetyltrimethylammonium bromide in white oil to prepare reaction solution C; the mass ratio of cetyltrimethylammonium bromide to white oil is 1:100 - 150; S4: Directly mix reaction solution A and reaction solution C, heat and stir at a temperature of 75 - 95 °C, and evenly inject reaction solution B into the reactor with a peristaltic pump during the heating and stirring process to obtain a milky yellow suspension; In this step, reaction solution B is completely added within 60 min, the stirring rate is controlled at 200 - 400 r / min, and the reaction time is controlled at 18 - 24 h; the volume ratio of reaction solution A to reaction solution C is controlled at 1:1 - 5; the molar ratio of phenol in reaction solution A to formaldehyde in reaction solution B is controlled at 1:1.2 - 1.8; S5: Perform solid - liquid separation on the milky yellow suspension obtained in step S4, wash the separated solid product with one of ethanol, acetone, and dichloromethane multiple times, and dry the washed and separated solid product at 30 - 60 °C to obtain a carbon aerogel microsphere product.

2. The preparation method of a carbon aerogel microsphere with controllable particle size according to claim 1, characterized in that: In step S3, the stirring and dissolving rate is 150 - 200 r / min, and the stirring and dissolving time is 5 - 10 min.

3. The preparation method of a carbon aerogel microsphere with controllable particle size according to claim 1 or 2, characterized in that: In step S2, the stirring temperature is controlled at 30 - 60 °C, and the stirring rate is controlled at 15 - 30 rpm.

4. The preparation method of a carbon aerogel microsphere with controllable particle size according to claim 3, wherein: Taking the phenol dosage as 1 mol, the dosages of the remaining components are as follows: 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 2.0 - 2.5 g of sodium carboxymethyl cellulose, 3.2 - 4.0 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose is less than 2.0, and the peristaltic pump rotation speed is 3 - 6 mL / min. The particle size D50 of the prepared carbon aerogel microspheres is between 25 - 100 microns.

5. The preparation method of a carbon aerogel microsphere with controllable particle size according to claim 3, characterized in that: Taking the phenol dosage as 1 mol, the dosages of the remaining components are as follows: 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 2.2 - 3.0 g of sodium carboxymethyl cellulose, 3.0 - 3.8 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose is less than 1.7, and the peristaltic pump rotation speed is 3 - 6 mL / min. The particle size D50 of the prepared carbon aerogel microspheres is between 100 - 300 microns.

6. The preparation method of a carbon aerogel microsphere with controllable particle size according to claim 3, characterized in that: With the dosage of phenol being 1 mol, and the dosages of the remaining components being as follows: 97 - 146 g of formaldehyde solution, 0.97 - 14.0 g of melamine, 0.9 - 2.9 g of sodium hydroxide, 90 - 500 mL of white oil, 3.2 - 4.0 g of sodium carboxymethyl cellulose, 2.5 - 3.0 g of cetyltrimethylammonium bromide, and the mass ratio of cetyltrimethylammonium bromide to sodium carboxymethyl cellulose being less than 1.0, with the peristaltic pump speed being 8 - 12 mL / min, the prepared carbon aerogel microspheres have a D50 particle size greater than 300 microns.