阅读说明：本技术 增强型二氧化硅气凝胶的制备方法、增强型二氧化硅气凝胶及其应用 (Preparation method of enhanced silica aerogel, enhanced silica aerogel and application thereof ) 是由 杨金兰 于 2019-11-29 设计创作，主要内容包括：本发明涉及气凝胶技术领域,具体是一种增强型二氧化硅气凝胶的制备方法、增强型二氧化硅气凝胶及其应用。将硅源、烷氧基硅烷化苯基试剂、醇类有机溶剂、水混合均匀后,经过酸化和碱化步骤制得湿凝胶,再经过老化、溶剂置换、表面改性后,干燥得到增强型二氧化硅气凝胶；所述烷氧基硅烷化苯基试剂选自1,4-二(三甲氧基硅基)苯、1,4-二(三乙氧基硅基)苯和4,4’-二(乙氧基甲硅烷)-1,1’-联苯中的一种或几种。本发明的二氧化硅气凝胶具有较好的力学强度,湿凝胶可以在常压下干燥而不发生破坏,节省设备投资、提高生产效率,降低生产成本,可以在保温材料、隔热材料、废气处理材料、废水处理材料、催化剂领域的应用。(The invention relates to the technical field of aerogel, in particular to a preparation method of enhanced silicon dioxide aerogel, the enhanced silicon dioxide aerogel and application thereof. Uniformly mixing a silicon source, an alkoxy silanization phenyl reagent, an alcohol organic solvent and water, preparing wet gel through acidification and alkalization, aging, solvent replacement and surface modification, and drying to obtain enhanced silicon dioxide aerogel; the alkoxy silanization phenyl reagent is selected from one or more of 1, 4-bis (trimethoxysilyl) benzene, 1, 4-bis (triethoxysilyl) benzene and 4,4 '-bis (ethoxysilyl) -1, 1' -biphenyl. The silicon dioxide aerogel of the invention has better mechanical strength, the wet gel can be dried under normal pressure without damage, the equipment investment is saved, the production efficiency is improved, the production cost is reduced, and the silicon dioxide aerogel can be applied to the fields of heat insulation materials, waste gas treatment materials, waste water treatment materials and catalysts.)

1. The preparation method of the enhanced silica aerogel is characterized by comprising the following steps: uniformly mixing a silicon source, an alkoxy silanization phenyl reagent, an alcohol organic solvent and water, preparing wet gel through acidification and alkalization, aging, absolute ethyl alcohol replacement and surface modification, and drying to obtain enhanced silicon dioxide aerogel; the alkoxy silanization phenyl reagent is selected from one or more of 1, 4-bis (trimethoxysilyl) benzene, 1, 4-bis (triethoxysilyl) benzene and 4,4 '-bis (ethoxysilyl) -1, 1' -biphenyl.

2. The method for preparing a reinforced silica aerogel according to claim 1, characterized in that: the molar ratio of the silicon source, the alkoxy silanization phenyl reagent, the alcohol organic solvent and the water is 1:0.1-0.5:8-15: 4-8.

3. The method for preparing a reinforced silica aerogel according to claim 2, characterized in that: the molar ratio of the silicon source, the alkoxy silanization phenyl reagent, the alcohol organic solvent and the water is 1:0.13-0.45:9-12: 5-7.

4. The method for preparing a reinforced silica aerogel according to claim 1, characterized in that: the silicon source is selected from one or more of methyl orthosilicate, ethyl orthosilicate, sodium silicate, methyltrimethoxysilane, methyltriethoxysilane and polysiloxane.

5. The method for preparing a reinforced silica aerogel according to claim 1, characterized in that: the alcohol organic solvent is selected from one or more of methanol, ethanol, isopropanol and n-butanol.

6. The method for preparing a reinforced silica aerogel according to claim 1, characterized in that: the modifier used for surface modification is trimethylchlorosilane or hexamethyldisilazane.

7. The method for preparing a reinforced silica aerogel according to claim 1, characterized in that: the drying is one of supercritical drying, freeze drying or normal pressure drying.

8. The method for preparing a reinforced silica aerogel according to claim 7, characterized in that: the drying is carried out under normal pressure, and is carried out for 1.5-3 hours at the temperature of 50 ℃, 85 ℃ and 120 ℃ respectively.

9. A reinforced silica aerogel obtained by the method for producing a reinforced silica aerogel according to any one of claims 1 to 8.

10. The use of the reinforced silica aerogel according to claim 9 in the fields of thermal insulation materials, waste gas and wastewater treatment, catalysts, pharmaceuticals and electronic products.

Technical Field

The invention relates to the technical field of aerogel, in particular to a preparation method of enhanced silicon dioxide aerogel, the enhanced silicon dioxide aerogel and application thereof.

Background

Aerogel generally refers to a light nano solid material which is formed by mutually gathering nano-scale ultrafine particles to form a nano-porous network structure, and a gaseous dispersion medium is filled in the network structure. Aerogel is a solid, but 99% of its volume is gas, appearing like a cloud in appearance, and is also known as "solid smoke".

The silicon dioxide aerogel is the most common aerogel, is a light-weight nano porous amorphous solid material with excellent heat-proof and heat-insulating properties, has the porosity of 80-99.8 percent, the typical size of holes of 1-100nm, the specific surface area of 200-1000m2/g, the density of 3kg/m3 and the room-temperature heat conductivity coefficient of 0.012 Wm-1K-1. Due to the characteristics, the silicon dioxide aerogel has wide application prospects in the fields of insulating materials, chemistry, electronic products, medicines and the like.

The silica aerogel is generally a silicon source, such as methyl orthosilicate, ethyl orthosilicate, sodium silicate and the like, and is obtained by respectively hydrolyzing solvent and water under an acidic condition, condensing and aging the solvent and the water under an alkaline condition, replacing the solvent with the solvent, modifying the surface of the solvent and drying the solvent and the water. Because the wet gel before drying has insufficient mechanical strength, and the gel network structure is easy to collapse and destroy during drying, the drying of the wet gel needs to adopt a supercritical drying technology or a freeze drying technology. However, the supercritical drying technology and the freeze-drying technology are expensive in equipment, low in efficiency and high in cost, so that researchers in the industry hope to improve the mechanical strength of the silica wet gel, so that the normal-pressure drying technology can be used, the production cost can be greatly reduced, and the large-scale production can be realized.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of enhanced silica aerogel, the prepared enhanced silica aerogel can be dried under normal pressure, the equipment investment is saved, the production efficiency is improved, the production cost is reduced, and the large-scale production of the silica aerogel can be realized.

Another object of the present invention is to provide a reinforced silica aerogel having better mechanical strength.

It is also an object of the present invention to provide the use of reinforced silica aerogels.

The invention adopts the following technical scheme:

the preparation method of the enhanced silica aerogel comprises the following steps of uniformly mixing a silicon source, an alkoxy silanization phenyl reagent, an alcohol organic solvent and water, preparing wet gel through acidification and alkalization, aging, absolute ethyl alcohol replacement and surface modification, and drying to obtain the enhanced silica aerogel; the alkoxy silanization phenyl reagent is selected from one or more of 1, 4-bis (trimethoxysilyl) benzene, 1, 4-bis (triethoxysilyl) benzene and 4,4 '-bis (ethoxysilyl) -1, 1' -biphenyl.

Preferably, the molar ratio of the silicon source, the alkoxy silanization phenyl reagent, the alcohol organic solvent and the water is 1:0.1-0.5:8-15: 4-8.

More preferably, the molar ratio of the silicon source, the alkoxy silanized phenyl reagent, the alcohol organic solvent and the water is 1:0.13-0.45:9-12: 5-7.

Preferably, the silicon source is selected from one or more of methyl orthosilicate, ethyl orthosilicate, sodium silicate, methyltrimethoxysilane, methyltriethoxysilane and polysiloxane. In a further preferred embodiment, the silicon source is selected from methyl orthosilicate, ethyl orthosilicate or sodium silicate.

Preferably, the alcohol organic solvent is selected from one or more of methanol, ethanol, isopropanol and n-butanol. Further preferred is a case where the alcoholic organic solvent is selected from ethanol and isopropanol.

The acidification is to add organic acid or inorganic acid into the reaction system, so that the pH of the reaction system is 2-4, and the adopted organic acid or inorganic acid can be at least one selected from hydrochloric acid, nitric acid, dilute sulfuric acid, acetic acid, formic acid and oxalic acid.

The alkalization is to add inorganic base or organic base into the reaction system to make the pH of the reaction system be 8-12, and the adopted inorganic base or organic base can be at least one selected from potassium hydroxide, sodium hydroxide, ammonia water, potassium carbonate, sodium carbonate and tetramethyl ammonium hydroxide.

The specific treatment mode of aging can be aging the wet gel in an environment of 30-90 ℃ for 1-3 hours.

Replacing anhydrous ethanol by aging, adding anhydrous ethanol into wet gel, soaking wet gel for 1-2 hr, and filtering to remove excessive solvent.

Preferably, the modifier used for surface modification is trimethylchlorosilane or hexamethyldisilazane. The surface modifier is dissolved in the normal hexane according to the volume ratio of the modifier to the normal hexane of 1:5-10, and the modification treatment time is 1-5 hours at normal temperature.

Preferably, the drying is one of supercritical drying, freeze drying or atmospheric drying.

More preferably, the drying is carried out by drying under normal pressure, and drying for 1.5-3 hours at 50 ℃, 85 ℃ and 120 ℃ respectively in sequence.

The reinforced silica aerogel obtained by the method for preparing a reinforced silica aerogel according to any one of the above embodiments.

The application of enhancement mode silica aerogel in insulation material, waste gas waste water treatment field, catalyst field, medicine field, electronic product field among the above-mentioned embodiment.

The invention has the beneficial effects that:

(1) the phenyl or biphenyl alkoxy silane containing a rigid structure and a conventional silicon source are subjected to cohydrolysis condensation, so that the rigidity of the three-dimensional network structure of the wet gel is improved, the contraction and collapse of the gel network structure caused by the action of capillary force during solvent evaporation are effectively avoided when the wet gel is dried under normal pressure, the equipment investment is saved, the production efficiency is improved, the production cost is reduced, and the method is suitable for large-scale production.

(2) The compressive strength of the obtained enhanced silica aerogel reaches over 0.7MPa, and is improved by over 17 times compared with that of the conventional silica aerogel; the bending strength reaches more than 1.3MPa, and compared with the conventional silicon dioxide aerogel, the bending strength is improved by more than 30 times.

Detailed Description

The technical solution of the present invention is further illustrated and described by the following detailed description.