CN112142058A - Method for preparing silica aerogel material by self-combustion method - Google Patents

Method for preparing silica aerogel material by self-combustion method Download PDF

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CN112142058A
CN112142058A CN202011020081.3A CN202011020081A CN112142058A CN 112142058 A CN112142058 A CN 112142058A CN 202011020081 A CN202011020081 A CN 202011020081A CN 112142058 A CN112142058 A CN 112142058A
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silica
gel
silicon dioxide
acid
fiber composite
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CN112142058B (en
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史继超
李中皓
孙鹏
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Shanghai Institute of Technology
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C01B33/158—Purification; Drying; Dehydrating
    • C01B33/1585—Dehydration into aerogels
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/152—Preparation of hydrogels
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
    • C01B33/157—After-treatment of gels
    • C01B33/159—Coating or hydrophobisation
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    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/06—Quartz; Sand
    • C04B14/064—Silica aerogel
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    • C04B30/00—Compositions for artificial stone, not containing binders
    • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
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    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0045—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by a process involving the formation of a sol or a gel, e.g. sol-gel or precipitation processes
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/12—Surface area
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    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/32—Thermal properties
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    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
    • C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors

Abstract

The invention discloses a method for preparing silicon dioxide aerogel by an auto-combustion method, which is characterized in that aging liquid is added into the silicon dioxide aerogel to age the silicon dioxide aerogel so as to obtain aged silicon dioxide aerogel; putting the aged silica gel into a surface modification liquid, and performing solvent replacement and surface modification to obtain modified silica wet gel; under the condition of oxygen enrichment, placing the modified silica wet gel on a porous plate or in a pipeline for heat dissipation; and (3) igniting the modified silica wet gel by an external fire source to completely burn the silica wet gel in a self-propagating way, and finally obtaining the hydrophobic nano porous silica aerogel. The hydrophobic nano-porous silica aerogel prepared by the method has the advantages of simple process, low production cost, short production period and contribution to large-scale production of the hydrophobic nano-porous silica material, and the prepared hydrophobic nano-porous silica aerogel has excellent performances of low density, large specific surface area, low heat conductivity coefficient and the like.

Description

Method for preparing silica aerogel material by self-combustion method
Technical Field
The invention relates to a method for preparing a silicon dioxide aerogel material by a self-combustion method, belonging to the technical field of nano porous materials.
Background
The nano porous silica aerogel is a continuous three-dimensional network structure formed by mutually polymerizing nano-scale particles, and has special nano micropores and a skeleton structure, so that the heat conduction efficiency, the convection heat transfer efficiency and the radiation heat transfer efficiency of the nano porous silica aerogel are effectively limited, and the nano porous silica aerogel has a very low heat conduction coefficient which can be as low as 0.013W/(m.K) at normal temperature and normal pressure and is a solid material with the lowest heat conduction coefficient in the world at present. In addition, the silica aerogel also shows unique physical properties in the aspects of sound, light, electricity and the like, so that the silica aerogel has very wide application potential in the fields of industry, civil use, building, aerospace, military and the like.
The preparation of silica aerogels generally comprises two steps: preparing the gel by a sol-gel method, and drying the gel to obtain the aerogel. The drying of the gel is a key step in the preparation process, and mainly comprises a supercritical drying technology, a normal-pressure drying technology, a grading reduced-pressure drying technology and the like. The supercritical drying technology is an aerogel product production technology widely adopted at present, but the method has high requirements on equipment, high cost and large early investment, and the high-temperature and high-pressure state has danger, so that the production cost is high, the wide application of the silica aerogel product is limited, and the development of the aerogel industry is hindered. The normal pressure drying method is popular with researchers due to the advantages of simple operation, low cost and the like, but the preparation method has long period and low production efficiency, and the mass production of aerogel products is limited. The staged reduced pressure drying technique is similar to the atmospheric drying method, and although the production cost and the equipment requirement are lower than those of the supercritical method, the production period and the efficiency are also the same. Therefore, how to improve the production efficiency of the normal pressure drying technology and shorten the production period is a great problem of the current technology.
The sol-gel self-combustion method is a novel material synthesis method combining the traditional sol-gel method and the self-combustion method. The method takes a complexing agent in a precursor as fuel, and the gel is properly heated to initiate self-combustion to form a product in the combustion. The method has the characteristics of short reaction time, simple and convenient operation steps, cheap raw materials, high yield and the like, and is very suitable for large-scale synthesis of the nano powder material. The method is widely applied to synthesis of various oxide nano materials. Therefore, the research on the synthesis of the nano particles by utilizing the sol-gel self-combustion method has the potential of providing a simple and efficient synthesis process of the sulfide nano material, and has stronger application and academic values.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the existing preparation method of the silicon dioxide aerogel product has the problems of long preparation period, low production efficiency and the like, and limits the mass production of the aerogel product.
In order to solve the above problems, the present invention provides a method for preparing silica aerogel by auto-combustion, which is characterized by comprising the following steps:
step 1): adding an aging liquid into the silica gel, and aging at 20-100 ℃ to obtain aged silica gel;
step 2): placing the aged silica gel into a surface modification liquid, and performing solvent replacement and surface modification at 20-100 ℃ to obtain modified silica wet gel;
step 3): under the condition of oxygen enrichment, placing the modified silica wet gel on a porous plate or in a pipeline for heat dissipation;
step 4): and (3) igniting the modified silica wet gel by an external fire source to completely burn the silica wet gel in a self-propagating way, and finally obtaining the hydrophobic nano porous silica aerogel.
Preferably, the silica gel in step 1) is prepared from a silicon source by any one of the following methods:
the method comprises the following steps: dissolving a silicon source and alcohol in deionized water to obtain a mixed solution; dropwise adding acid into the mixed solution under the stirring condition, and standing at the temperature of 20-100 ℃ to obtain silicon dioxide gel;
the second method comprises the following steps: dissolving a silicon source, alcohol and acid in deionized water to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol; dropwise adding an alkaline catalyst into the silica sol under the stirring condition, adjusting the pH value to be neutral, and standing at the temperature of 20-100 ℃ to obtain silica gel;
the third method comprises the following steps: diluting a silicon source with deionized water at normal temperature, and adjusting the pH value to 4-8 with acid to obtain hydrosol; standing the hydrosol at normal temperature to form silicon dioxide gel, and then washing with deionized water;
the method four comprises the following steps: diluting a silicon source with water at normal temperature, and adjusting the pH value to 1-5 by using acid or strong acid type cation exchange resin to fully hydrolyze sodium silicate in the solution into silicic acid monomer solution; adding an alkaline catalyst into a silicic acid monomer solution to adjust the pH value to 5.5-8 to form silicon dioxide gel, and then washing with deionized water.
More preferably, the silicon source is an organic silicon source or an inorganic silicon source.
Further, the organic silicon source is organic siloxane, and comprises one or a mixture of several of methyl orthosilicate, ethyl orthosilicate, methyl triethoxysilane, ethyl trimethoxysilane, polysilicate, dichlorodimethylsilane, dichlorodiethylsilane, dichlorodipropylsilane, dichlorodiphenylsilane, chlorotrimethylsilane, chlorotriethylsilane, monochloropropylsilane, monochlorotriphenylsilane, dihydroxydimethylsilane, dihydroxydiethylsilane, dihydroxydiphenylsilane, dimethyldiphenylsilane, hexamethylcyclotrisiloxane, hexamethyldisiloxane, hexamethyldisilylamine, hexamethyldisiloxane and polysilane; the inorganic silicon source is water glass.
Furthermore, the modulus of the water glass is 2-4.
More preferably, in the first method, the volume ratio of the silane to the alcohol to the deionized water is 1 (1-16) to 0.01-6.
More preferably, in the second method, the volume ratio of the silicon source, the alcohol, the acidic catalyst and the deionized water is 1 (1-16): (0.1-4): 0.01-6).
More preferably, the volume ratio of the silicon source to the deionized water in the third method and the fourth method is 1 (4-10).
More preferably, the alcohol in the first and second methods is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol.
More preferably, the acid in the first method, the second method, the third method and the fourth method is at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, hydrofluoric acid and oxalic acid.
Further, the concentration of the acid is 0.1-6 mol/L.
More preferably, the basic catalyst in the second and fourth methods is at least one of ammonia water, lithium hydroxide, sodium hydroxide, potassium hydroxide and organic amine.
Preferably, the aging solution in step 1) is any one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and organosiloxane or a mixed solution thereof with water.
Preferably, the surface modification liquid in the step 2) consists of a silane coupling agent and a low surface tension solvent in a volume ratio of 1 (1-20); the silane coupling agent is any one or more of trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisiloxane, hexamethyldisilazane and hexamethyldisiloxane, and the low-surface-tension solvent is any one or more of methanol, ethanol, isopropanol, n-hexane, cyclohexane and n-heptane.
Preferably, the oxygen-rich condition in step 3) is realized by: natural conditions, the action of a blast device or the additional design of oxygen gas circuit for combustion supporting; the porous plate/pipeline is made of metal, ceramic, concrete or cement.
Preferably, the external ignition source in the step 4) is at least one of spark ignition, infrared radiation ignition, ignition for reaching the natural ignition point of the material and ignition by an external ignition source.
Preferably, the aged silica gel in the step 2) is crushed into uniform powder with the particle size of 5 μm to 1mm before being put into the surface modification liquid.
Preferably, the density of the hydrophobic nano porous silica aerogel obtained in the step 4) is 30-200 kg/m3The specific surface area is 300-1000 m2The thermal conductivity coefficient is 0.015-0.04W/m.k.
The invention also provides application of the method for preparing the silicon dioxide aerogel by the self-combustion method in preparing the aerogel composite heat-insulating material, which is characterized by comprising the following steps of:
step a): dissolving a silicon source, alcohol and acid in deionized water to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
step b): immersing the reinforced fiber substrate into the silica sol for standing, and then adding an alkaline catalyst to adjust the pH value to 5.5-8 to form silica gel, so as to obtain silica fiber composite gel;
step c): adding an aging solution into the silicon dioxide fiber composite gel, and aging at 20-100 ℃ to obtain aged silicon dioxide fiber composite gel;
step d): placing the aged silica fiber composite gel into a surface modification solution, and performing surface modification and solvent replacement at 20-100 ℃ to obtain modified silica fiber composite gel;
step e): washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
step f): under the condition of oxygen enrichment, placing the modified fiber composite gel on a porous plate or in a pipeline for heat dissipation;
step g): and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
Preferably, the density of the hydrophobic nano porous silica fiber composite aerogel material prepared in the step g) is 40-200 kg/m3The thickness is 0.1 to 10mm, and the thermal conductivity is 0.015 to 0.03W/m.k.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention firstly provides a preparation method for preparing the hydrophobic nano porous silica material by adopting a self-combustion method, the process is simple, the production cost is low, the production period is short, and the large-scale production of the hydrophobic nano porous silica material is facilitated.
2. According to the invention, the preparation of the wet gel is realized by a one-step method, and the silica aerogel material is prepared in a simple manner of self-combusting the wet gel by a simple method of additionally adding a fire device or a fire source.
3. The self-combustion method adopted by the invention has high combustion speed, and greatly improves the production period of the silicon dioxide aerogel compared with other preparation technologies.
4. The silica composite aerogel material prepared by the invention has the excellent performances of low density, large specific surface area, low heat conductivity coefficient and the like, and can be applied to producing composite heat-insulating materials.
Detailed Description
In order to make the invention more comprehensible, preferred embodiments are described in detail below.
Example 1
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring methyl orthosilicate, methanol and deionized water according to a volume ratio of 20mL to 0.2mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) dropwise adding 0.02mL of hydrofluoric acid into the mixed solution obtained in the step (1) under stirring, and standing at the temperature of 30 ℃ to obtain silicon dioxide gel;
(3) adding methanol and methyl orthosilicate aging solution into the obtained silica gel, and continuing aging at 30 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 5-micron powder by a rapid crusher at a rotating speed of 3000 r/min;
(5) putting silica gel powder into a surface modification solution formed by trimethylchlorosilane and normal hexane (the volume ratio is 10mL:10mL), and performing surface modification and solvent replacement at 50 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous aluminum metal plate or in an aluminum metal pipeline under natural ventilation conditions;
(7) the wet gel was ignited by a lighter and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3Specific surface area of 900m2The thermal conductivity is 0.02W/m.k.
Example 2
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring ethyl orthosilicate, ethanol and deionized water according to a volume ratio of 10mL to 160mL to 10mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) dropwise adding 0.8mL of hydrofluoric acid into the mixed solution obtained in the step (1) under stirring, and standing at 50 ℃ to obtain silicon dioxide gel;
(3) adding aging solution of ethanol and ethyl orthosilicate into the obtained silica gel, and continuing aging at 50 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 100 mu m powder by a rapid crusher at a rotating speed of 100 r/min;
(5) putting the silica gel powder into a surface modification solution formed by hexamethyldisiloxane and n-heptane (the volume ratio is 20mL:100mL), and carrying out surface modification and solvent replacement at 80 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous ceramic plate or in a ceramic pipeline under a natural ventilation condition;
(7) the wet gel was ignited by infrared lamp radiation and allowed to self-burn completely to yield a silica aerogel material.
The silica aerogel material prepared in this example had a density of 50kg/m3Specific surface area of 1000m2(ii) a thermal conductivity of 0.015W/m.k.
Example 3
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) weighing methyltriethoxysilane, n-propanol and deionized water according to the volume ratio of 10mL to 40mL to 5mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) dropwise adding 0.5mL of hydrofluoric acid into the mixed solution obtained in the step (1) under stirring, and standing at 60 ℃ to obtain silicon dioxide gel;
(3) adding the aging solution of n-propanol and methyltriethoxysilane into the obtained silica gel, and continuing aging at 75 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 200 mu m powder by a rapid crusher at the rotating speed of 1000 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by dimethyldichlorosilane and n-heptane (the volume ratio is 2mL:40mL), and carrying out surface modification and solvent replacement at 70 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a cellular concrete slab under natural ventilation conditions;
(7) the wet gel was ignited by a match and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3Specific surface area of 800m2The thermal conductivity coefficient is 0.021W/m.k.
Example 4
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring ethyl trimethoxy silane, n-butanol and deionized water according to the volume ratio of 10mL to 80mL to 40mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) dropwise adding 0.5mL of hydrofluoric acid into the mixed solution obtained in the step (1) while stirring, and standing at the temperature of 20-100 ℃ to obtain silicon dioxide gel;
(3) adding the aging liquid of n-butyl alcohol and ethyltrimethoxysilane into the obtained silica gel, and continuing aging under the radiation of an infrared lamp to obtain aged silica gel;
(4) pulverizing the aged silica gel into uniform 300 μm powder;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by hexamethyldisilazane and cyclohexane (the volume ratio is 10mL:100mL), and carrying out surface modification and solvent replacement at 50 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a porous cement plate or in a cement pipeline under the natural ventilation condition;
(7) the wet gel was ignited by an electric ignition device and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 80kg/m3Specific surface area of 870m2The thermal conductivity was 0.022W/m.k.
Example 6
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring methyl orthosilicate, methanol, hydrochloric acid and deionized water according to a volume ratio of 20mL to 2mL to 0.2mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at the temperature of 20 ℃ to obtain silica gel;
(3) adding methanol and methyl orthosilicate aging solution into the obtained silica gel, and continuing aging at 20 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 5-micron powder by a rapid crusher at a rotating speed of 3000 r/min;
(5) putting silica gel powder into a surface modification solution formed by trimethylchlorosilane and normal hexane (the volume ratio is 10mL:10mL), and performing surface modification and solvent replacement at 20 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous aluminum metal plate or in an aluminum metal pipeline under natural ventilation conditions;
(7) the wet gel was ignited by a lighter and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3Specific surface area of 900m2The thermal conductivity is 0.02W/m.k.
Example 7
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring tetraethoxysilane, ethanol, phosphoric acid and deionized water according to the volume ratio of 10mL to 160mL to 40mL to 10mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at 50 ℃ to obtain silica gel;
(3) adding aging solution of ethanol and ethyl orthosilicate into the obtained silica gel, and continuing aging at 50 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 100 mu m powder by a rapid crusher at a rotating speed of 100 r/min;
(5) putting the silica gel powder into a surface modification solution formed by hexamethyldisiloxane and n-heptane (the volume ratio is 20mL:100mL), and carrying out surface modification and solvent replacement at 100 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous ceramic plate or in a ceramic pipeline under a natural ventilation condition;
(7) the wet gel was ignited by infrared lamp radiation and allowed to self-burn completely to yield a silica aerogel material.
The silica aerogel material prepared in this example had a density of 50kg/m3Specific surface area of 1000m2(ii) a thermal conductivity of 0.015W/m.k.
Example 8
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) weighing methyltriethoxysilane, n-propanol, nitric acid and deionized water according to the volume ratio of 10mL to 40mL to 3mL to 5mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at 70 ℃ to obtain silica gel;
(3) adding the aging solution of n-propanol and methyltriethoxysilane into the obtained silica gel, and continuing aging at 75 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 200 mu m powder by a rapid crusher at the rotating speed of 1000 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by dimethyldichlorosilane and n-heptane (the volume ratio is 2mL:40mL), and carrying out surface modification and solvent replacement at 70 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a cellular concrete slab under natural ventilation conditions;
(7) the wet gel was ignited by a match and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3Specific surface area of 800m2A thermal conductivity of 0.021W/m·k。
Example 9
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring ethyl trimethoxy silane, n-butanol, acetic acid and deionized water according to the volume ratio of 10mL to 80mL to 30mL to 40mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at 100 ℃ to obtain silica gel;
(3) adding the aging liquid of n-butyl alcohol and ethyltrimethoxysilane into the obtained silica gel, and continuing aging under the radiation of an infrared lamp to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 300 mu m powder by a rapid crusher at the rotating speed of 1500 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by hexamethyldisilazane and cyclohexane (the volume ratio is 10mL:100mL), and carrying out surface modification and solvent replacement at 50 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a porous cement plate or in a cement pipeline under the natural ventilation condition;
(7) the wet gel was ignited by an electric ignition device and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 80kg/m3Specific surface area of 870m2The thermal conductivity was 0.022W/m.k.
Example 10
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring polysilicate, isobutanol, oxalic acid and deionized water according to the volume ratio of 10mL to 80mL to 40mL to 10mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at 90 ℃ to obtain silica gel;
(3) adding the aging solution of n-butyl alcohol and ethyltrimethoxysilane into the obtained silica gel, and continuing aging under the radiation of a microwave generator to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 1000-micron powder by a rapid crusher at the rotating speed of 500 r/min;
(5) putting the silica gel powder into a surface modification solution formed by hexamethyldisiloxane and methanol (volume ratio is 10mL:100mL), and carrying out surface modification and solvent replacement at 60 ℃ to obtain modified silica wet gel;
(6) under the condition of natural ventilation, placing the modified wet gel in a composite structure device consisting of a porous aluminum metal plate and a ceramic pipeline;
(7) the wet gel was ignited by a lighter and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 60kg/m3Specific surface area of 850m2The thermal conductivity coefficient is 0.020W/m.k.
Example 11
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) 5mL of water glass (modulus: 3.3) was weighed, diluted with 30mL of deionized water, and filtered. 2mol/L dilute sulfuric acid is adjusted to pH value of 7;
(2) standing the water glass aqueous solution obtained in the step (1) at room temperature for 12 hours, and washing the water glass aqueous solution for 6 times by using deionized water to obtain silicon dioxide gel;
(3) adding methanol and methyl orthosilicate aging solution into the obtained silica gel, and continuing aging at 20 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 5-micron powder by a rapid crusher at a rotating speed of 3000 r/min;
(5) putting silica gel powder into a surface modification solution formed by trimethylchlorosilane and normal hexane (the volume ratio is 10mL:10mL), and performing surface modification and solvent replacement at 20 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous aluminum metal plate or in an aluminum metal pipeline under natural ventilation conditions;
(7) the wet gel was ignited by a lighter and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3, a specific surface area of 900m2/g, and a thermal conductivity of 0.02W/m.k.
Example 12
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) 10mL of industrial water glass (modulus 2.5) is weighed, diluted with 40mL of deionized water, and filtered. 2mol/L diluted hydrochloric acid is adjusted to pH value of 8;
(2) standing the water glass aqueous solution obtained in the step (1) at room temperature for 48 hours, and washing the water glass aqueous solution for 6 times by using deionized water to obtain silicon dioxide gel;
(3) adding aging solution of ethanol and ethyl orthosilicate into the obtained silica gel, and continuing aging at 50 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 100 mu m powder by a rapid crusher at a rotating speed of 100 r/min;
(5) putting the silica gel powder into a surface modification solution formed by hexamethyldisiloxane and n-heptane (the volume ratio is 20mL:100mL), and carrying out surface modification and solvent replacement at 100 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous ceramic plate or in a ceramic pipeline under a natural ventilation condition;
(7) the wet gel was ignited by infrared lamp radiation and allowed to self-burn completely to yield a silica aerogel material.
The silica aerogel material prepared in this example had a density of 50kg/m3, a specific surface area of 1000m2/g, and a thermal conductivity of 0.015W/m.k.
Example 13
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) 10mL of industrial water glass (modulus 4) is weighed, diluted with 50mL of deionized water, and filtered. 5mol/L dilute sulfuric acid is adjusted to pH value of 7;
(2) standing the water glass aqueous solution obtained in the step (1) at room temperature for 12 hours, and washing the water glass aqueous solution for 6 times by using deionized water to obtain silicon dioxide gel;
(3) adding the aging solution of n-propanol and methyltriethoxysilane into the obtained silica gel, and continuing aging at 75 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 200 mu m powder by a rapid crusher at the rotating speed of 1000 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by dimethyldichlorosilane and n-heptane (the volume ratio is 2mL:40mL), and carrying out surface modification and solvent replacement at 70 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a cellular concrete slab under natural ventilation conditions;
(7) the wet gel was ignited by a match and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in the example has the density of 100kg/m3, the specific surface area of 800m2/g and the thermal conductivity of 0.021W/m.k.
Example 14
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) 10mL of industrial water glass (modulus: 3.0) was weighed, diluted with 40mL of deionized water, and filtered. Adjusting the pH value to 8 by using 5mol/L diluted hydrochloric acid;
(2) standing the water glass aqueous solution obtained in the step (1) at room temperature for 24 hours, and washing with deionized water for 4-6 times to obtain silicon dioxide gel;
(3) adding the aging liquid of n-butyl alcohol and ethyltrimethoxysilane into the obtained silica gel, and continuing aging under the radiation of an infrared lamp to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 300 mu m powder by a rapid crusher at the rotating speed of 1500 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by hexamethyldisilazane and cyclohexane (the volume ratio is 10mL:100mL), and carrying out surface modification and solvent replacement at 50 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a porous cement plate or in a cement pipeline under the natural ventilation condition;
(7) the wet gel was ignited by an electric ignition device and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in the example has the density of 80kg/m3, the specific surface area of 870m2/g and the thermal conductivity of 0.022W/m.k.
Example 15
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring 10mL of industrial water glass (the modulus is 3.3), diluting with 50mL of deionized water, and filtering; then adjusting the pH value to 1 by using 6mol/L phosphoric acid;
(2) adding 1mol/L sodium hydroxide solution into the water glass aqueous solution obtained in the step (1), adjusting the pH value to 5.5 to form hydrogel, and washing for 6 times by using deionized water to obtain silicon dioxide gel;
(3) adding aging solution of ethanol and ethyl orthosilicate into the obtained silica gel, and continuing aging at 50 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 100 mu m powder by a rapid crusher at a rotating speed of 100 r/min;
(5) putting the silica gel powder into a surface modification solution formed by hexamethyldisiloxane and n-heptane (the volume ratio is 20mL:100mL), and carrying out surface modification and solvent replacement at 100 ℃ to obtain modified silica wet gel;
(6) placing the modified wet gel on a porous ceramic plate or in a ceramic pipeline under a natural ventilation condition;
(7) the wet gel was ignited by infrared lamp radiation and allowed to self-burn completely to yield a silica aerogel material.
The silica aerogel material prepared in this example had a density of 50kg/m3Specific surface area of 1000m2(ii) a thermal conductivity of 0.015W/m.k.
Example 16
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring 10mL of industrial water glass (the modulus is 2.5), diluting with 40mL of deionized water, and filtering; firstly, deionized water at 80 ℃ is used for passing through a 732# strong acid type cation resin column, and then a water glass solution heated to 45 ℃ is passed through the column to obtain silica sol with the pH value of 3;
(2) adding 0.5mol/L ammonia water solution into the silica sol obtained in the step (1), and adjusting the pH value to 8 to form hydrogel;
(3) adding the aging solution of n-propanol and methyltriethoxysilane into the obtained silica gel, and continuing aging at 75 ℃ to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 200 mu m powder by a rapid crusher at the rotating speed of 1000 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by dimethyldichlorosilane and n-heptane (the volume ratio is 2mL:40mL), and carrying out surface modification and solvent replacement at 70 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a cellular concrete slab under natural ventilation conditions;
(7) the wet gel was ignited by a match and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 100kg/m3Specific surface area of 800m2/g，The thermal conductivity was 0.021W/m.k.
Example 17
A method for preparing a silica aerogel material by an auto-combustion method comprises the following steps:
(1) measuring 10mL of industrial water glass (modulus is 4), diluting with 40mL of deionized water, and filtering; then adjusting the pH value to 5 by using 6mol/L nitric acid;
(2) adding 1mol/L ammonia water solution into the water glass water solution obtained in the step (1), adjusting the pH value to 8 to form hydrogel, and washing for 6 times by using deionized water to obtain silicon dioxide gel;
(1) measuring ethyl trimethoxy silane, n-butanol, acetic acid and deionized water according to the volume ratio of 10mL to 80mL to 30mL to 40mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) slowly dropwise adding an alkaline catalyst into the silica sol obtained in the step (1) under stirring, adjusting the pH value to be neutral, and standing at 100 ℃ to obtain silica gel;
(3) adding the aging liquid of n-butyl alcohol and ethyltrimethoxysilane into the obtained silica gel, and continuing aging under the radiation of an infrared lamp to obtain aged silica gel;
(4) crushing the aged silica gel into uniform 300 mu m powder by a rapid crusher at the rotating speed of 1500 r/min;
(5) putting the silicon dioxide gel powder into a surface modification solution formed by hexamethyldisilazane and cyclohexane (the volume ratio is 10mL:100mL), and carrying out surface modification and solvent replacement at 50 ℃ to obtain modified silicon dioxide wet gel;
(6) placing the modified wet gel on a porous cement plate or in a cement pipeline under the natural ventilation condition;
(7) the wet gel was ignited by an electric ignition device and allowed to self-combust completely to give the silica aerogel material.
The silica aerogel material prepared in this example had a density of 80kg/m3Specific surface area of 870m2The thermal conductivity was 0.022W/m.k.
Example 18
A preparation method for preparing aerogel composite heat insulation insulating material by a self-combustion method comprises the following steps:
(1) measuring methyl orthosilicate, methanol, hydrochloric acid and deionized water according to a volume ratio of 20mL to 2mL to 0.2mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) immersing the glass fiber substrate into the silica sol obtained in the step (1) and standing for a period of time, and then adding ammonia water to adjust the pH value to 6.5 to form silica gel, so as to obtain silica fiber composite gel;
(3) adding an aging liquid into the silica fiber composite gel obtained in the step (2), and continuously aging at 80 ℃ to obtain an aged silica fiber composite gel;
(4) putting the silicon dioxide fiber composite gel into a modification solution, and performing surface modification and solvent replacement at 55 ℃ to obtain modified silicon dioxide fiber composite gel;
(5) washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
(6) under the condition of oxygen enrichment and ventilation, placing the modified fiber composite gel on a porous plate or in a pipeline with good heat dissipation;
(7) and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
The density of the silica aerogel composite prepared in this example was 190kg/m3The thickness was 0.2mm, and the thermal conductivity was 0.022W/m.k.
Example 19
A preparation method for preparing aerogel composite heat insulation insulating material by a self-combustion method comprises the following steps:
(1) measuring tetraethoxysilane, ethanol, oxalic acid and deionized water according to the volume ratio of 10mL to 160mL to 40mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) immersing an aluminum silicate fiber substrate into the silica sol obtained in the step (1) and standing for a period of time, and then adding a potassium hydroxide solution to adjust the pH value to 7 to form silica gel, so as to obtain silica fiber composite gel;
(3) adding an aging liquid into the silica fiber composite gel obtained in the step (2), and continuously aging at 80 ℃ to obtain an aged silica fiber composite gel;
(4) putting the silicon dioxide fiber composite gel into a modification liquid, and performing surface modification and solvent replacement at 80 ℃ to obtain modified silicon dioxide fiber composite gel;
(5) washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
(6) under the condition of oxygen enrichment and ventilation, placing the modified fiber composite gel on a porous plate or in a pipeline with good heat dissipation;
(7) and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
The density of the silica aerogel composite prepared in this example was 80kg/m3The thickness is 10mm, and the thermal conductivity is 0.02W/m.k.
Example 20
A preparation method for preparing aerogel composite heat insulation insulating material by a self-combustion method comprises the following steps:
(1) measuring water glass, n-propanol, nitric acid and deionized water according to a volume ratio of 10mL to 40mL to 3mL to 5mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) immersing the glass fiber substrate into the silica sol obtained in the step (1) and standing for a period of time, and then adding a sodium hydroxide solution to adjust the pH value to 6.5 to form silica gel, so as to obtain silica fiber composite gel;
(3) adding an aging liquid into the silica fiber composite gel obtained in the step (2), and continuously aging at 30 ℃ to obtain an aged silica fiber composite gel;
(4) putting the silicon dioxide fiber composite gel into a modification liquid, and performing surface modification and solvent replacement at 80 ℃ to obtain modified silicon dioxide fiber composite gel;
(5) washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
(6) under the condition of oxygen enrichment and ventilation, placing the modified fiber composite gel on a porous plate or in a pipeline with good heat dissipation;
(7) and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
The density of the silica aerogel composite prepared in this example was 190kg/m3The thickness is 5mm, and the thermal conductivity is 0.025W/m.k.
Example 21
A preparation method for preparing aerogel composite heat insulation insulating material by a self-combustion method comprises the following steps:
(1) measuring ethyl trimethoxy silane, n-butanol, acetic acid and deionized water according to the volume ratio of 10mL to 80mL to 30mL to 40mL, and stirring to obtain a mixed solution, so that the mixed solution is fully reacted to obtain silicon dioxide sol;
(2) immersing the rock wool fiber base material into the silica sol obtained in the step (1) and standing for a period of time, and then adding an ethylamine solution to adjust the pH value to 5 to form silica gel, so as to obtain silica fiber composite gel;
(3) adding an aging liquid into the silica fiber composite gel obtained in the step (2), and continuously aging at 80 ℃ to obtain an aged silica fiber composite gel;
(4) putting the silicon dioxide fiber composite gel into a modification solution, and performing surface modification and solvent replacement at 55 ℃ to obtain modified silicon dioxide fiber composite gel;
(5) washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
(6) under the condition of oxygen enrichment and ventilation, placing the modified fiber composite gel on a porous plate or in a pipeline with good heat dissipation;
(7) and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
The density of the silica aerogel composite prepared in this example was 190kg/m3The thickness is 4mm, and the thermal conductivity is 0.03W/m.k.
Example 22
A preparation method for preparing aerogel composite heat insulation insulating material by a self-combustion method comprises the following steps:
(1) measuring ethyl trimethoxy silane, isobutanol, oxalic acid and deionized water according to the volume ratio of 10mL to 80mL to 40mL to 10mL, stirring to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
(2) immersing the carbon fiber substrate into the silica sol obtained in the step (1) and standing for a period of time, and then adding ammonia water to adjust the pH value to 7 to form silica gel, so as to obtain silica fiber composite gel;
(3) adding an aging liquid into the silica fiber composite gel obtained in the step (2), and continuously aging at 80 ℃ to obtain an aged silica fiber composite gel;
(4) putting the silicon dioxide fiber composite gel into a modification liquid, and performing surface modification and solvent replacement at 80 ℃ to obtain modified silicon dioxide fiber composite gel;
(5) washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
(6) under the condition of oxygen enrichment and ventilation, placing the modified fiber composite gel on a porous plate or in a pipeline with good heat dissipation;
(7) and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
The density of the silica aerogel composite prepared in this example was 70kg/m3The thickness was 1mm, and the thermal conductivity was 0.022W/m.k.

Claims (14)

1. A method for preparing silicon dioxide aerogel by an auto-combustion method is characterized by comprising the following steps:
step 1): adding an aging liquid into the silica gel, and aging at 20-100 ℃ to obtain aged silica gel;
step 2): placing the aged silica gel into a surface modification liquid, and performing solvent replacement and surface modification at 20-100 ℃ to obtain modified silica wet gel;
step 3): under the condition of oxygen enrichment, placing the modified silica wet gel on a porous plate or in a pipeline for heat dissipation;
step 4): and (3) igniting the modified silica wet gel by an external fire source to completely burn the silica wet gel in a self-propagating way, and finally obtaining the hydrophobic nano porous silica aerogel.
2. The method for preparing silica aerogel by auto-combustion as claimed in claim 1, wherein the silica gel in the step 1) is prepared from a silicon source by any one of the following methods:
the method comprises the following steps: dissolving a silicon source and alcohol in deionized water to obtain a mixed solution; dropwise adding acid into the mixed solution under the stirring condition, and standing at the temperature of 20-100 ℃ to obtain silicon dioxide gel;
the second method comprises the following steps: dissolving a silicon source, alcohol and acid in deionized water to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol; dropwise adding an alkaline catalyst into the silica sol under the stirring condition, adjusting the pH value to be neutral, and standing at the temperature of 20-100 ℃ to obtain silica gel;
the third method comprises the following steps: diluting a silicon source with deionized water at normal temperature, and adjusting the pH value to 4-8 with acid to obtain hydrosol; standing the hydrosol at normal temperature to form silicon dioxide gel, and then washing with deionized water;
the method four comprises the following steps: diluting a silicon source with water at normal temperature, and adjusting the pH value to 1-5 by using acid or strong acid type cation exchange resin to fully hydrolyze sodium silicate in the solution into silicic acid monomer solution; adding an alkaline catalyst into a silicic acid monomer solution to adjust the pH value to 5.5-8 to form silicon dioxide gel, and then washing with deionized water.
3. The self-combustion method for preparing silica aerogel according to claim 2, wherein the silicon source is an organic silicon source or an inorganic silicon source; the organic silicon source is organic siloxane which comprises one or a mixture of more of methyl orthosilicate, ethyl orthosilicate, methyltriethoxysilane, ethyltrimethoxysilane, polysilicate, dichlorodimethylsilane, dichlorodiethylsilane, dichlorodipropylsilane, dichlorodiphenylsilane, chlorotrimethylsilane, chlorotriethylsilane, monochloropropylsilane, monochlorotriphenylsilane, dihydroxydimethylsilane, dihydroxydiethylsilane, dihydroxydiphenylsilane, dimethyldiphenylsilane, hexamethylcyclotrisiloxane, hexamethyldisilylamine, hexamethyldisiloxane and polysilazane; the inorganic silicon source is water glass.
4. The self-combustion method for preparing silica aerogel according to claim 3, wherein the water glass has a modulus of 2 to 4.
5. The self-combustion method for preparing silica aerogel according to claim 2, wherein the volume ratio of silane, alcohol and deionized water in the first method is 1 (1-16) to (0.01-6); in the second method, the volume ratio of the silicon source, the alcohol, the acid catalyst and the deionized water is 1 (1-16): 0.1-4): 0.01-6; in the third method and the fourth method, the volume ratio of the silicon source to the deionized water is 1 (4-10).
6. The self-combustion method for preparing silica aerogel according to claim 2, wherein the alcohol in the first and second methods is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol; in the first method, the second method, the third method and the fourth method, the acid is at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, hydrofluoric acid and oxalic acid, and the concentration of the acid is 0.1-6 mol/L; the alkaline catalyst in the second method and the fourth method is at least one of ammonia water, lithium hydroxide, sodium hydroxide, potassium hydroxide and organic amine.
7. The self-combustion method for preparing silica aerogel according to claim 1, wherein the aging liquid in step 1) is any one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and organosiloxane, or a mixture thereof with water.
8. The method for preparing the silica aerogel through the self-combustion method according to claim 1, wherein the surface modification solution in the step 2) consists of a silane coupling agent and a low surface tension solvent in a volume ratio of 1 (1-20); the silane coupling agent is any one or more of trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisiloxane, hexamethyldisilazane and hexamethyldisiloxane, and the low-surface-tension solvent is any one or more of methanol, ethanol, isopropanol, n-hexane, cyclohexane and n-heptane.
9. The method for preparing silica aerogel by auto-combustion as claimed in claim 1, wherein the oxygen-rich condition in the step 3) is realized by: natural conditions, the action of a blast device or the additional design of oxygen gas circuit for combustion supporting; the porous plate/pipeline is made of metal, ceramic, concrete or cement.
10. The self-combustion method for preparing silica aerogel according to claim 1, wherein the external fire source in step 4) is ignited by at least one of spark ignition, infrared radiation ignition, ignition to reach the natural ignition point of the material, and ignition from an external fire source.
11. The self-combustion method for preparing silica aerogel according to claim 1, wherein the aged silica gel in the step 2) is pulverized into uniform powder having a particle size of 5 μm to 1mm before being put into the surface modification liquid.
12. The self-combustion method for preparing silica aerogel according to claim 1, wherein the density of the hydrophobic nanoporous silica aerogel obtained in the step 4) is 30 to 200kg/m3The specific surface area is 300-1000 m2The thermal conductivity coefficient is 0.015-0.04W/m.k.
13. Use of the self-combustion process for the preparation of silica aerogel according to any of claims 1 to 10 for the preparation of aerogel composite thermal insulation, comprising the steps of:
step a): dissolving a silicon source, alcohol and acid in deionized water to obtain a mixed solution, and fully reacting to obtain silicon dioxide sol;
step b): immersing the reinforced fiber substrate into the silica sol for standing, and then adding an alkaline catalyst to adjust the pH value to 5.5-8 to form silica gel, so as to obtain silica fiber composite gel;
step c): adding an aging solution into the silicon dioxide fiber composite gel, and aging at 20-100 ℃ to obtain aged silicon dioxide fiber composite gel;
step d): placing the aged silica fiber composite gel into a surface modification solution, and performing surface modification and solvent replacement at 20-100 ℃ to obtain modified silica fiber composite gel;
step e): washing the wet gel for multiple times by using a low surface tension solvent for the modified fiber composite gel, and standing to obtain modified silicon dioxide fiber composite gel;
step f): under the condition of oxygen enrichment, placing the modified fiber composite gel on a porous plate or in a pipeline for heat dissipation;
step g): and (3) igniting the modified silica fiber composite gel by an external fire source to completely burn the modified silica fiber composite gel in a self-propagating way, thereby finally obtaining the hydrophobic nano porous silica fiber composite aerogel material.
14. The use according to claim 13, wherein the hydrophobic nanoporous silica fiber composite aerogel material prepared in step g) has a density of 40 to 200kg/m3The thickness is 0.1 to 10mm, and the thermal conductivity is 0.015 to 0.03W/m.k.
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CN105621419A (en) * 2014-12-02 2016-06-01 北京建工新型建材有限责任公司 Ambient preparation method for silica aerogel powder
CN110697724A (en) * 2019-11-22 2020-01-17 上海应用技术大学 Silicon dioxide aerogel and preparation method thereof

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CN113563049A (en) * 2021-08-23 2021-10-29 中南大学 Hydrophobic silica aerogel composite material with high thermal stability and low calorific value and preparation method thereof
CN114477195A (en) * 2022-01-18 2022-05-13 中国科学院工程热物理研究所 Preparation method of hydrophobic silica aerogel powder
CN114906854A (en) * 2022-05-10 2022-08-16 纳诺科技有限公司 Neutral aerogel powder and preparation method thereof
CN114906854B (en) * 2022-05-10 2023-09-22 纳诺科技有限公司 Neutral aerogel powder and preparation method thereof
CN115849392A (en) * 2022-12-31 2023-03-28 福建师范大学泉港石化研究院 Silicon dioxide aerogel and preparation method thereof

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