Preparation method of aerogel modified nano porous material

Abstract

The invention discloses a preparation method of an aerogel modified nano porous material. Comprising the following steps: heating a sodium silicate solution to a reaction temperature, adding SiO2 aerogel and a modifier, then adding calcium hydroxide slurry, uniformly mixing, and carrying out a reaction. And after the reaction is finished, carrying out solid-liquid separation, soaking a filter cake in absolute ethyl alcohol, carrying out aging treatment, filtering, and drying to obtain the aerogel modified nano-porous material. The obtained product is inorganic powder, and has the characteristics of large specific surface area, high porosity, low heat conductivity coefficient, non-combustibility and the like. The method provided by the invention not only solves the bottleneck problems of difficult dispersion and poor strength in SiO2 aerogel application, but also significantly reduces the production cost of the composite material; in addition, the method is simple and flexible to operate, relatively low in equipment requirement, relatively high in operability and easy to industrially popularize and use.

Description

Technical Field

[0001] The present invention belongs to the field of new materials and relates to a preparation method of an aerogel-modified nanoporous material. Background Art

[0002] Since the 21st century, with the increasing demand for energy, energy consumption has also been increasing. However, the rapid growth of energy consumption has caused an energy supply crisis and a series of environmental problems. "Energy conservation and emission reduction" has become the primary task faced by humanity worldwide.

[0003] The new materials industry is the foundation of a manufacturing powerhouse and the cornerstone and forerunner of the development of high-tech industries. As one of the new materials, aerogel has a porosity of more than 90%. The porous structure gives rise to excellent heat insulation, sound absorption, and adsorption properties. At the same time, different skeleton components endow aerogel with excellent optical, electrical, magnetic, and biological properties at the nanoscale. It can be widely used in many fields such as national defense, aerospace, chemical engineering, and construction. It is a key material for the green and low-carbon development and product quality upgrade in these fields in the future. Due to the restriction of the production process, aerogel materials generally have high production costs and expensive product prices, which limits their application in most industries. Summary of the Invention

[0004] In order to solve the many problems existing in the application of SiO2 aerogel materials, the present invention prepares a nanoporous material with excellent heat preservation function under certain process conditions. By controlling the production process conditions, products of different specifications and uses can be obtained. This new type of nanoporous material can be widely used in the production of fireproof building insulation materials, which can greatly reduce the thermal conductivity of the insulation materials and improve the heat preservation performance and market competitiveness of the products.

[0005] Combined with the application requirements, the present invention combines aerogel materials with the self-developed production process of nanoporous silicon to produce and develop an aerogel-modified nanoporous composite material with excellent heat insulation performance. Among them, SiO2 aerogel is used as a template agent, and nanoporous silicon is wrapped on the outer layer of SiO2 aerogel particles. The product not only has a low thermal conductivity, is fireproof and flame-retardant, but also has a low cost, which can solve the problems of low strength, difficult dispersion, and high cost of aerogel materials, and provides a functional material with high cost performance, fireproof, and excellent heat insulation performance for the field of insulation materials.

[0006] The above object of the present invention is achieved by the following technical solutions: In view of the urgent demand for non-combustible and highly efficient insulation materials in the current building insulation material market, the present invention makes full use of the characteristics of aerogel materials and nanoporous silicon, and adopts a new synthesis process and in-situ synthesis technology to prepare an aerogel-modified nanoporous material with non-combustibility and low thermal conductivity, which greatly improves the product cost performance and market competitiveness.

[0007] The present invention provides a preparation method of an aerogel-modified nanoporous material. Through this method, a new material with non-combustibility and low thermal conductivity can be obtained. The preparation method of the nanoporous material is as follows: First, add a qualified sodium silicate solution to a reaction tank. After heating to the required reaction temperature, add SiO2 aerogel and a modifier so that the SiO2 aerogel is uniformly dispersed in the sodium silicate solution, and the sodium silicate solution enters the pores in the aerogel particles. Then add calcium hydroxide slurry, and Ca 2+ generated by the dissolution of calcium hydroxide reacts with SiO3 2- in the system, and under certain conditions, they combine to form CaSiO3·nH2O with a porous structure. The calcium silicate crystal particles uniformly wrap the aerogel particles, and the two form a tight and firm combination. After the reaction is completed, solid-liquid separation is carried out. The filter cake is soaked and aged with absolute ethanol, and then filtered and dried to obtain the aerogel-modified nanoporous material.

[0008] Specifically, the preparation method includes the following steps: Heat the sodium silicate solution to a certain temperature, sequentially add SiO2 aerogel, a modifier, and calcium hydroxide, mix evenly, and react to obtain a product slurry; the obtained product slurry is sequentially dehydrated, aged, centrifuged, and dried to obtain the aerogel-modified nanoporous material; the modifier is one or more of aluminum sulfate, aluminum chloride, or sodium aluminate.

[0009] The obtained product is an inorganic powder, which has characteristics such as a large specific surface area, a high porosity, a low thermal conductivity, and non-combustibility. The surface and internal pores of the product particles are well-developed, and the special structure endows it with excellent thermal insulation performance. The product itself is non-toxic, fireproof and flame-retardant, and does not contain harmful chemical substances. Through production process control, modification or processing, products with different functional characteristics can be obtained. It is a new type of functional material with great development potential and can be widely used in the production of industrial and building thermal insulation materials.

[0010] Preferably, the heating temperature is 40-60°C.

[0011] Preferably, the SiO2 aerogel is a hydrophobic SiO2 aerogel, with an average particle size <15 μm, a specific surface area >600 m 2 / g, a porosity >95%, and the dosage of SiO2 aerogel is 0.5-10% (based on the total amount of absolutely dry sodium silicate and calcium hydroxide).

[0012] The modifier is one or more of aluminum sulfate, aluminum chloride, or sodium aluminate, and is purchased from the market; the water glass is commercial liquid water glass, and the calcium hydroxide powder is a common chemical grade product purchased from the market.

[0013] Preferably, in the sodium silicate, SiO2 aerogel, modifier and calcium hydroxide, the material ratio requirements are as follows: the Ca / Si molar ratio of calcium hydroxide and sodium silicate is 1.0 - 3.0, and the Al / Si molar ratio of sodium aluminate and sodium silicate is 0.1 - 0.6. The purpose of controlling the calcium-silicon ratio and aluminum-silicon ratio is mainly to achieve the high-porosity structure and pore size range of the material.

[0014] Preferably, after adding the above production materials to the reaction tank according to the process requirements, start timing. After reacting for 2 - 4 hours, the material can be discharged to obtain the product slurry. Then, pump the slurry to a plate and frame filter press or centrifuge for dehydration to obtain the wet cake of the product. Soak the wet cake in absolute ethanol for 24 hours and then perform solid-liquid separation to obtain the aged cake. Finally, use a drying device to dry and classify the aged cake to obtain nano-porous silicon powders of different specifications.

[0015] The aerogel-modified nano-porous material prepared by the above preparation method.

[0016] To improve the drying efficiency, efficiently remove the moisture and solution in the pores, and reduce the damage to the pore structure of the product during the drying process, preferably, the drying of the product uses a microwave drying device, and strictly control the drying temperature ≤ 80°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses aerogel as a template agent, and in-situ synthesizes nano-porous calcium silicate on the surface and inside the pores of aerogel particles by a hydrothermal method, developing a new type of nano-porous composite material, which solves the bottleneck problems of difficult dispersion and poor strength in the application of SiO2 aerogel.

[0018] In the present invention, the addition amount of aerogel is small, and the sodium silicate and calcium hydroxide used in the synthesis of the composite material are both inexpensive materials. Therefore, the production cost of the composite material is greatly reduced, only one-third of that of the aerogel material, providing a new functional material with high cost performance for the thermal insulation industry.

[0019] The present invention has simple and flexible operation, relatively low requirements for equipment, strong operability, and is easy to be popularized and adopted industrially. Description of the Drawings

[0020] Figure 1 It is the SEM diagram of the nano-porous material in Example 4 of the present invention. Detailed Embodiments

[0021] The present invention will be further described below in conjunction with specific implementation embodiments. The advantages and features of the present invention will become clearer with the description. However, these embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and forms of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but these modifications and substitutions all fall within the protection scope of the present invention.

[0022] Example 1 A preparation method of an aerogel-modified nanoporous material, comprising the following steps: The water glass indexes for production are: modulus n = 3.0, SiO2 concentration 23%; the purity of calcium hydroxide raw material > 98%; the used modifier is prepared into a solution with a solid content of 10% for standby; the average particle size of hydrophobic SiO2 aerogel is 9.0 μm, specific surface area 650 m 2 / g, porosity 96.2%; the specific production process is as follows: (1) Add an appropriate amount of water glass to the reaction tank, turn on the stirring and heating steam, heat to 60 °C, and sequentially add SiO2 aerogel powder, sodium aluminate solution and calcium hydroxide, and stir evenly; the Ca / Si molar ratio of calcium hydroxide and sodium silicate in the mixed material is 2.5, the Al / Si molar ratio of sodium aluminate and sodium silicate is 0.1, and the aerogel addition amount is 2% of the total mass of anhydrous sodium silicate and calcium hydroxide; after reacting for 2.0 h, discharge the material to obtain a product slurry.

[0023] (2) Pump the product slurry to a centrifuge for dehydration, convey the filter cake to an aging tank, then add anhydrous ethanol for aging treatment, and the aging time is 24 h.

[0024] (3) Pump the aged slurry to a centrifuge for dehydration to obtain a qualified filter cake.

[0025] (4) Dry and classify the aged wet cake at 60 °C - 80 °C to obtain aerogel-modified nanoporous materials of different specifications.

[0026] The thermal conductivity of the aerogel-modified nanoporous material prepared by this method is 0.048 w / m·k.

[0027] Example 2 A preparation method of an aerogel-modified nanoporous material, comprising the following steps: The water glass indexes for production are: modulus n = 3.0, SiO2 concentration 23%; the purity of calcium hydroxide raw material > 98%; the used modifier is prepared into a solution with a solid content of 10% for standby; the average particle size of SiO2 aerogel is 9.0 μm, specific surface area 650 m 2 / g, porosity 96.2%; the specific production process is as follows: (1) Add an appropriate amount of water glass to the reaction tank, turn on the stirring and heating steam, heat to 60 °C, and sequentially add SiO2 aerogel powder, sodium aluminate solution, and calcium hydroxide, and stir evenly; the Ca / Si molar ratio of calcium hydroxide and sodium silicate in the mixed material is 2.5, the Al / Si molar ratio of sodium aluminate and sodium silicate is 0.1, and the addition amount of aerogel is 5% of the total mass of dry calcium hydroxide and sodium silicate; after reacting for 2.0 h, discharge the material to obtain the product slurry.

[0028] (2) Pump the product slurry to a centrifuge for dehydration, convey the filter cake to the aging tank, then add absolute ethanol for aging treatment, and the aging time is 24 h.

[0029] (3) Pump the aged slurry to a centrifuge for dehydration to obtain a qualified filter cake.

[0030] (4) Dry and classify the aged wet cake at 60 °C - 80 °C to obtain aerogel-modified nanoporous materials of different specifications.

[0031] The thermal conductivity of the aerogel-modified nanoporous material prepared by this method is 0.040 w / m·k.

[0032] Example 3 A preparation method of an aerogel-modified nanoporous material includes the following steps: The water glass index for production is: modulus n = 2.5, SiO2 concentration 23%; the purity of calcium hydroxide raw material > 98%; the used modifier is prepared into a solution with a solid content of 10% for standby; the average particle size of SiO2 aerogel is 9.0 μm, the specific surface area is 650 m 2 / g, and the porosity is 96.2%; the specific production process is as follows: (1) Add an appropriate amount of water glass to the reaction tank, turn on the stirring and heating steam, heat to 60 °C, and sequentially add SiO2 aerogel powder, sodium aluminate solution, and calcium hydroxide, and stir evenly; the Ca / Si molar ratio of calcium hydroxide and sodium silicate in the mixed material is 1.5, the Al / Si molar ratio of sodium aluminate and sodium silicate is 0.1, and the addition amount of aerogel is 8% of the total mass of dry sodium silicate and calcium hydroxide; after reacting for 3.5 h, discharge the material to obtain the product slurry.

[0033] (2) Pump the product slurry to a centrifuge for dehydration, convey the filter cake to the aging tank, then add absolute ethanol for aging treatment, and the aging time is 24 h.

[0034] (3) Pump the aged slurry to a centrifuge for dehydration to obtain a qualified filter cake.

[0035] (4) Dry and classify the aged wet cake at 60 °C - 80 °C to obtain aerogel-modified nanoporous materials of different specifications.

[0036] The thermal conductivity of the aerogel-modified nanoporous material prepared by this method is 0.035 w / m·k.

[0037] Example 4 A preparation method of an aerogel-modified nanoporous material, comprising the following steps: The indicators of the water glass used in production are: modulus n = 2.5, SiO2 concentration 23%; the purity of the calcium hydroxide raw material > 98%; the modifier used is prepared into a solution with a solid content of 10% for standby; the average particle size of the SiO2 aerogel is 9.0 μm, the specific surface area is 650 m 2 / g, and the porosity is 96.2%; the specific production process is as follows: (1) Add an appropriate amount of water glass to the reaction tank, turn on the stirring and heating steam, heat to 60 °C, and sequentially add SiO2 aerogel powder, sodium aluminate solution, and calcium hydroxide, and stir evenly; the Ca / Si molar ratio of calcium hydroxide and sodium silicate in the mixed material is 1.5, the Al / Si molar ratio of sodium aluminate and sodium silicate is 0.1, and the addition amount of the aerogel is 10% of the total mass of dry sodium silicate and calcium hydroxide; after reacting for 4.0 h, discharge the material to obtain a product slurry.

[0038] (2) Pump the product slurry to a centrifuge for dehydration, convey the filter cake to an aging tank, then add anhydrous ethanol, and carry out aging treatment for 24 h.

[0039] (3) Pump the aged slurry to a centrifuge for dehydration to obtain a qualified filter cake.

[0040] (4) Dry and classify the aged wet cake at 60 °C - 80 °C to obtain aerogel-modified nanoporous materials of different specifications, and the SEM diagram of the material is as Figure 1 shown in.

[0041] The thermal conductivity of the aerogel-modified nanoporous material prepared by this method is 0.030 w / m·k.

Claims

1. A preparation method of an aerogel-modified nanoporous material, characterized in that, Using sodium silicate, calcium hydroxide, aerogel and a modifier as the main raw materials, where the aerogel is used as a templating agent, nano-porous calcium silicate is in-situ synthesized on the surface and inside the pores of the aerogel particles by a hydrothermal method.

2. The preparation method of an aerogel-modified nanoporous material according to claim 1, wherein, The modulus n of the sodium silicate is n≥2.

5.

3. The preparation method of an aerogel-modified nanoporous material according to claim 1, characterized in that, The aerogel is a hydrophobic SiO2 aerogel powder with an average particle size < 15 μm, a specific surface area > 600 m 2 / g, and a porosity > 95%.

4. The preparation method of an aerogel-modified nanoporous material according to claim 1, characterized in that, The modifier is an aluminum salt, selected from one or more of aluminum sulfate, aluminum chloride or sodium aluminate.

5. The preparation method of an aerogel-modified nanoporous material according to any one of claims 1-4, characterized in that, The preparation process is as follows: First, add a qualified sodium silicate solution to the reaction tank. After heating to the reaction temperature of 40 - 60 °C, then sequentially add SiO2 aerogel, the modifier and calcium hydroxide, stir evenly, and react while maintaining the stirring state. After the reaction is completed, perform solid-liquid separation on the product slurry. The filter cake is aged with absolute ethanol, and then filtered, dried and classified to obtain an aerogel-modified nano-porous material.

6. The preparation method of an aerogel-modified nanoporous material according to claim 5, characterized in that, The ratio requirements of calcium hydroxide and sodium silicate are: the Ca / Si molar ratio is 1.0 - 3.0, and the Al / Si molar ratio in sodium aluminate and sodium silicate is 0.1 - 0.

6.

7. The preparation method of an aerogel-modified nanoporous material according to claim 6, wherein The mass of the SiO2 aerogel accounts for 0.5 - 10% of the total mass of the absolutely dry sodium silicate and calcium hydroxide.

8. The preparation method of an aerogel-modified nanoporous material according to claim 5, characterized in that, The reaction time is 2 - 4 h; preferably, after the reaction is completed, pump the product slurry to a plate and frame filter press or a centrifuge for dehydration to obtain a wet cake of the product, and soak the wet cake with absolute ethanol for 24 h.

9. The preparation method of an aerogel-modified nanoporous material according to claim 5, characterized in that, The aerogel-modified nano-porous material is dried by microwave drying, and the drying temperature is ≤80 °C.

10. An aerogel-modified nano-porous material prepared by the preparation method according to any one of claims 6 - 9.

Images