SILICA AEROGEL PREPARATION METHOD AND AEROGEL PREPARED USING SAID METHOD

Abstract

A preparation method for a silica aerogel, comprising the following steps: A) raw material containing a solid silicon source and an alkaline solution is used to produce an aerogel precursor after mixing; and B) the aerogel precursor is dried to obtain a silica aerogel. An improved silica aerogel preparation method, comprising the following steps: A) a cation exchange resin and a silicate solution are used as raw materials and mixed; B) the mixed material is allowed to stand to obtain an aerogel precursor; and C) the aerogel precursor is dried to obtain a silica aerogel.

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. A method for preparing silica aerogel, comprising the following steps: A) mixing uniformly mixed silicon phosphate, sodium silicate and water with gel core particles to obtain a precursor under a sealed condition; the gel core particles comprise one or more of white carbon black and silica powder; B) drying the precursor to obtain a silica aerogel.

42. The method according to claim 1, wherein, a mass ratio of the silicon phosphate to the sodium silicate is (1-100): 100; a weight ratio of the gel core particles to the sodium silicate is (1-50): 100.

43. The method according to claim 1, wherein, a mass ratio of the silicon phosphate to the sodium silicate is (5-50): 100.

44. The method according to claim 1, wherein, a weight ratio of the gel core particles to the sodium silicate is (5-20): 100.

45. The method according to claim 1, wherein, drying the precursor to obtain the aerogel product by an atomized drying or a natural drying.

46. The method according to claim 1, wherein, drying the precursor by an atomized drying to obtain the aerogel product, and a drying temperature of the atomized drying is 200-500° C.

47. The method according to claim 1, wherein, drying the precursor by a natural drying to obtain the aerogel product, and a drying temperature of the natural drying is room temperature.

48. The method according to claim 1, comprising the following steps: A) mixing silicon phosphate and sodium silicate uniformly under a sealed condition and then dissolving in water to obtain a system A; adding one or more of white carbon black and silica powder into the system A under a sealed condition to obtain a precursor; B) drying the precursor to obtain a silica aerogel.

49. The method according to claim 1, comprising the following steps: (1) mixing uniformly mixed silicon polyphosphate, sodium silicate and water with the gel core particles to obtain a precursor under a sealed condition; the gel core particles comprise one or more of white carbon black and silica powder; (2) drying the precursor to obtain a silica aerogel.

50. The method according to claim 9, comprising the following steps: (1) mixing silicon polyphosphate and sodium silicate uniformly under a sealed condition and then dissolving in water to obtain a system A; adding one or more of white carbon black and silica powder into the system A under airtight condition to obtain a precursor; (2) drying the precursor to obtain a silica aerogel.

51. The method according to claim 1, comprising the following steps: (1) mixing uniformly mixed silicon phosphate, silicon polyphosphate, sodium silicate and water with gel core particles to obtain a precursor under the sealed condition; the gel core particles comprise one or more of white carbon black and silica powder; (2) drying the precursor to obtain a silica aerogel.

52. The method according to claim 11, comprising the following steps: (1) mixing silicon polyphosphate, silicon phosphate and sodium silicate uniformly under a sealed condition and then dissolving in water to obtain a system A; adding one or more of white carbon black and silica fume into the system A under airtight condition to obtain a precursor; (2) drying the precursor to obtain a silica aerogel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 Flow diagram for the basic Embodiment.

[0067] FIG. 2 Flow diagram for the improved Embodiment 1.

[0068] FIG. 3 Flow diagram for the improved Embodiment 2.

[0069] FIG. 4 Flow diagram for the improved Embodiment 3.

[0070] FIG. 5 Flow diagram for a preferable Embodiment of the improved Embodiment 4.

[0071] FIG. 6 SEM photograph of the silica aerogel in example 7.

[0072] FIG. 7 SEM photograph of the silica aerogel in example 8.

[0073] FIG. 8 SEM photograph of the silica aerogel in example 9.

[0074] FIG. 9 SEM photograph of the silica aerogel in example 4.

[0075] FIG. 10 SEM photograph of the silica aerogel in example 5.

[0076] FIG. 11 SEM photograph of the silica aerogel in example 6.

[0077] FIG. 12 SEM photograph of the silica aerogel in example 13.

[0078] FIG. 13 SEM photograph of the silica aerogel in example 14.

[0079] FIG. 14 SEM photograph of the silica aerogel in example 15.

[0080] FIG. 15 SEM photograph of the silica aerogel in example 16.

[0081] FIG. 16 Flow diagram for the improved Embodiment 4.

DETAIL DESCRIPTION OF THE INVENTION

Example 1

[0082] 28 g of sodium silicate and 50 g of white carbon black modified by methyl methacrylate were evenly mixed. 100 g of ethyl acetate and 100 g of water were added to the mixture. The reaction was carried out at a reaction temperature of 60° C. with continuous stirring for 4 h in a closed container, so as to obtain a precursor.

[0083] The precursor was dried at a drying temperature of 180° C. for 60 min by microwave-hot-air drying, so as to obtain an aerogel powder with a water content lower than 0.01%.

Example 2

[0084] 18 g of sodium silicate and 40 g of white carbon black modified by methyl methacrylate were evenly mixed. 90 g of ethyl acetate and 90 g of water were added to the mixture. The reaction was carried out at a reaction temperature of 50° C. with continuous stirring for 5 h in a closed container, so as to obtain a precursor.

[0085] The precursor was dried at a drying temperature of 200° C. for 40 min using microwave-hot-air drying, so as to obtain an aerogel powder with a water content lower than 0.01%.

Example 3

[0086] 23 g of sodium silicate and 45 g of white carbon black modified by methyl methacrylate were evenly mixed. 95 g of ethyl acetate and 95 g of water were added to the mixture. The reaction was carried out at a reaction temperature of 55° C. with continuous stirring for 4.5 h in a closed container, so as to obtain a precursor.

[0087] The precursor was dried at a drying temperature of 190° C. for 50 min using microwave-hot-air drying, so as to obtain an aerogel powder with a water content lower than 0.01%.

Example 4

[0088] In an airtight container, 100 g of sodium silicate and 5 g of silicon phosphate were evenly mixed, and then dissolved in 100 L of deionized water, so as to obtain a system A. 10 g of nanoscale white carbon black was added into the system A to produce a precursor. The precursor was atomized and dried at a temperature of 500° C., so that silica aerogel powders were obtained after drying.

Example 5

[0089] In a closed container, 100 g of sodium silicate and 20 g of silicon phosphate were evenly mixed, and then dissolved in 100 mL of deionized water, so as to obtain system A. 16 g of nanoscale white carbon black and 4 g of silica powder were added into the system A to produce a precursor. The precursor was atomized and dried at a temperature of 300° C., so that silica aerogel powders were obtained after drying.

Example 6

[0090] In a closed condition, 100 g of sodium silicate and 10 g of silicon phosphate were evenly mixed, and then dissolved in 100 mL of deionized water, so as to obtain system A. 15 g of silica powder were added into the system A to produce a precursor. The precursor was atomized and dried at a temperature of 250° C., so that silica aerogel powders were obtained after drying.

Example 7

[0091] The sodium silicate solution with pH value of 11.3 was mixed with silica powder, stirred at a temperature of 35° C., and kept at this temperature under continuous stirring for 2 h. Consequently, the reaction was cooled to room temperature, and acetic acid was slowly added. The pH in the gelation process was controlled at 6.8, so that an aerogel precursor was obtained. The aerogel precursor was mixed with methane, and the water in the precursor was replaced by methane. Then the silica aerogel was dried using microwave drying, and the evaporated methane was cooled and recycled.

Example 8

[0092] The sodium silicate solution with pH value of 12 was mixed with fine silica powder, stirred at a temperature of 90° C., and kept at this temperature with continuous stirring for 2 h. Consequently, the reaction was cooled to room temperature, and citric acid was slowly added. The pH in the gelation process was controlled at 6.5, so that an aerogel precursor was obtained. The aerogel precursor was mixed with ethanol, and the water in the precursor was replaced by ethanol. Then the silica aerogel was dried using microwave drying, and the evaporated ethanol was cooled and recycled.

Example 9

[0093] The sodium silicate solution with pH value of 13.2 was mixed with white carbon black, stirred at a temperature of 65° C., and kept at this temperature under continuous stirring for 2 h. Consequently, the reaction was cooled to room temperature, and citric acid was slowly added. The pH in the gelation process was controlled at 6.7, so that an aerogel precursor was obtained. The aerogel precursor was mixed with dichloromethane, and the water in the precursor was replaced by dichloromethane. Then the silica aerogel was dried by microwave drying, and the evaporated dichloromethane was cooled and recycled. The SEM of the obtained silica aerogel was observed by scanning electron microscope, and its SEM photograph was obtained. It can be seen from the SEM photograph that the distribution solid silica source is uniform, forming a three-dimensional structure with a clear network structure, after recombination with sodium silicate. There are no solid particles with a large particle size in the fine silicon powder, indicating a complete reaction of the solid silica source with sodium silicate, and a three-dimensional porous structure was obtained.

Example 10

[0094] 2 mol of sodium silicate was added into 1 L of water to prepare sodium silicate solution. A cation exchange resin with a mass of 1/50 of sodium silicate was added into the sodium silicate solution. The reaction was carried out at a reaction temperature of 50° C. under a continuous stirring for 2 h. After the ion exchange reaction, filtration was performed and the filtrate was acidified and gelled. Then the ethanol was added for solvent substitution at a temperature of 25° C. for 30 h. Hexamethyldisilazane with a mass of ½ of sodium silicate was added, and the modification was performed at a temperature of 650° C. for 30 min, followed by a static aging of 4 d, so that a precursor was obtained.

[0095] The precursor was dried by natural drying at room temperature for 14 d, so as to obtain an aerogel powder with a water content lower than 0.01%.

[0096] An aerogel prepared by the above method.

Example 11

[0097] 3 mol of sodium silicate was added into 1 L of water to prepare sodium silicate solution. A cation exchange resin with a mass of 1/70 of sodium silicate was added into the sodium silicate solution. The reaction was carried out at a reaction temperature of 50° C. under a continuous stirring for 2 h. After the ion exchange reaction, filtration was performed and the filtrate was subjected to acidification and gelatinization. Then the ethanol was added for solvent substitution at a temperature of 25° C. for 30 h. Hexamethyldisilazane with a mass of ⅓ of sodium silicate was added, and the modification was performed at a temperature of 650° C. for 30 min, followed by a static aging of 4 d, so that a precursor was obtained.

[0098] The precursor was dried by natural drying at room temperature for 14 d, so as to obtain an aerogel powder with a water content lower than 0.01%.

Example 12

[0099] 1 mol of sodium silicate was added into 1 L of water to prepare sodium silicate solution. A cation exchange resin with a mass of 1/30 of sodium silicate was added into the sodium silicate solution. The reaction was carried out at a reaction temperature of 50° C. under a continuous stirring for 2 h. After the ion exchange reaction, filtration was performed and the filtrate was subjected to acidification and gelatinization. Then the ethanol was added for solvent substitution at a temperature of 25° C. for 30 h. Hexamethyldiazosilane with a mass of ¼ of sodium silicate was added, and the modification was performed at a temperature of 650° C. for 30 min, followed by a static aging of 4 d, so that a precursor was obtained.

[0100] The precursor was dried by natural drying at room temperature for 14 d, so as to obtain an aerogel powder with a water content lower than 0.01%.

Example 13

[0101] In a closed condition, 100 g of sodium silicate and log of silicon phosphate were evenly mixed, and then dissolved in 150 mL of deionized water, so as to obtain system A. 5 g of silica powder were added into the system A to produce a precursor. The precursor was atomized and dried at a temperature of 250° C., so that silica aerogel powders were obtained after drying.

Example 14

[0102] In a closed condition, 100 g of sodium silicate and 15 g of silicon phosphate were evenly mixed, and then dissolved in 100 mL of deionized water, so as to obtain system A. 1 g of silica powder were added into the system A to produce a precursor. The precursor was atomized and dried at a temperature of 400° C., so that silica aerogel powders were obtained after drying.

Example 15

[0103] In a closed condition, 100 g of sodium silicate and 10 g of silicon phosphate were evenly mixed, and then dissolved in 150 mL of deionized water, so as to obtain system A. 10 g of silica powder and 20 g of nanoscale white carbon black were added into the system A to produce a precursor. The precursor was coated on a solid surface, and dried by natural drying for 7 days, so that a silica aerogel film was obtained.

Example 16

[0104] In a closed condition, 100 g of sodium silicate and 5 g of silicon phosphate were evenly mixed, and then dissolved in 150 mL of deionized water, so as to obtain system A. 10 g of silica powder and 20 g of nanoscale white carbon black were added into the system A to produce a precursor. The precursor was coated on a solid surface, and dried by natural drying for 7 days, so that a silica aerogel film was obtained.

[0105] The silica aerogel powders obtained from examples 4-6 and 13-16 were observed under scanning electron microscope, and their SEMwere obtained, see FIGS. 9-15 (500 nm).

[0106] FIGS. 9-15 are the SEMs of the samples corresponding to examples 4-6 and examples 13-16, respectively. It can be seen that there are porous structures in all samples. It can be seen from FIGS. 11 and 12, the porous are evenly distributed, and there are no agglomeration. A three-dimensional porous structure is formed for all samples.

[0107] The specific surface area, porosity and thermal conductivity of aerogels obtained from examples 1-16 were measured. The results are shown in the following table.

TABLE-US-00001 TABLE Performance Measurements Specific surface Thermal Item area/(m.sup.2/g) Porosity conductivity/(w/mk) Example 1 800 95% 0.019 Example 2 850 95% 0.018 Example 3 820 95% 0.019 Example 4 950 95% 0.012 Example 5 860 96% 0.015 Example 6 870 95% 0.014 Example 7 500 87% 0.025 Example 8 839 92% 0.018 Example 9 856 93% 0.016 Example 10 900 92% 0.013 Example 11 800 91% 0.015 Example 12 700 90% 0.016 Example 13 920 95% 0.013 Example 14 900 95% 0.013 Example 15 870 96% 0.016 Example 16 900 95% 0.012 . . .