CN109748284A - A kind of preparation method of inorganic aerogels - Google Patents
A kind of preparation method of inorganic aerogels Download PDFInfo
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- CN109748284A CN109748284A CN201910236900.9A CN201910236900A CN109748284A CN 109748284 A CN109748284 A CN 109748284A CN 201910236900 A CN201910236900 A CN 201910236900A CN 109748284 A CN109748284 A CN 109748284A
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Abstract
The invention belongs to aeroge fields, more particularly to a kind of preparation method of inorganic aerogels, method includes the following steps: inorganic wet gel and dried medium are put into reaction kettle, it is heated to the temperature and pressure of setting under confined conditions, constant temperature is kept, stop heating and exhaust pressure relief later, obtains inorganic aerogels；The dried medium includes one of ethyl alcohol, water, acetone and n-hexane or a variety of；The volume ratio of the inorganic wet gel and dried medium is 1:(0.5~10)；The temperature set is 120~240 DEG C；The pressure set is 0.5~5.9MPa.Preparation method provided by the invention is by being in optimized selection the dry technical process of wet gel and condition, in the case where not needing using overcritical equipment, both the quality of product had been ensure that, the dry duration of wet gel is substantially reduced again, is suitble to promote the use of in the large-scale industrial production of inorganic aerogels.
Description
Technical field
The invention belongs to aeroge field more particularly to a kind of preparation methods of inorganic aerogels.
Background technique
Aeroge is made of the skeleton structure and pore structure of nano-scale, has extremely-low density, superelevation porosity, superelevation ratio
The excellent properties such as surface area, ultralow thermal conductivity, extra-low refractive index, ultralow transaudient rate, ultralow modulus, ultralow dielectric, make
It has wide application prospects in heat-barrier material, catalyst and catalyst carrier, raw impedance coupler material and other high-tech areas.
Currently, preparation bulk SiO2It mostly uses sol-gal process to prepare gel and then uses Supercritical Drying Technology and normal pressure
Preparation is dried in drying.It is effective as the supercritical drying drying method of mainstream that Kistler in 1931 has synthesized aeroge for the first time
It avoids because surface tension is destruction caused by aeroge network structure, but stringent to equipment requirement, condition controls and operates ratio
More difficult, production efficiency is relatively low and production cost is expensive, largely limits the practical application of aeroge.Using non-super
Critical drying means prepares bulk SiO2Aeroge has become research hotspot in recent years, and Gan Lihua et al. uses constant pressure and dry
Method impregnates obtained gel for 24 hours at 60 DEG C with ethyl alcohol, then to impregnate 4h at 70 DEG C of ethanol solution of TEOS, then by institute
Obtained gel freeze-day with constant temperature 72h at 70 DEG C, may finally obtain density is 212kg/m3Aeroge.Constant pressure and dry technique
Cost is relatively low, but in the drying process since the effect aerogel structure of capillary force is easy to happen contraction, deformation and fragmentation,
So that material specific surface area sharply declines, porosity is largely reduced, and drying time is generally longer.
Summary of the invention
In view of this, the purpose of the present invention is to provide a kind of preparation method of inorganic aerogels, system provided by the invention
Preparation Method is not necessarily to super critical condition, and length when drying, product property are good.
The present invention provides a kind of preparation methods of inorganic aerogels, comprising the following steps:
Inorganic wet gel and dried medium are put into reaction kettle, are heated to the temperature and pressure of setting under confined conditions,
Constant temperature is kept, and is stopped heating and exhaust pressure relief later, is obtained inorganic aerogels；
The dried medium includes one of ethyl alcohol, water, acetone and n-hexane or a variety of；
The volume ratio of the inorganic wet gel and dried medium is 1:(0.5~10)；
The temperature set is 120~240 DEG C；
The pressure set is 0.5~5.9MPa.
Preferably, the heating rate of the heating is 1~5 DEG C/min.
Preferably, the time that the constant temperature is kept is 1~3h.
Preferably, the rate of the exhaust pressure relief is 0.1~0.5MPa/min.
Preferably, further includes: forced air drying is carried out to the product after exhaust pressure relief.
Preferably, the inorganic wet gel includes SiO2Wet gel, TiO2Wet gel, SiO2/TiO2Compound wet gel and
Al2O3One of wet gel is a variety of.
Preferably, the SiO2Wet gel is prepared according to the following steps to obtain:
Esters of silicon acis and hydrochloric acid mix in a solvent carries out hydrolysis, obtains hydrolysate；
The hydrolysate and the reaction of Ammonia material mixing, reaction product carry out aging, obtain SiO2Wet gel.
Preferably, the TiO2Wet gel is prepared according to the following steps to obtain:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, and hydrolysate carries out aging, obtains TiO2Wet gel.
Preferably, the SiO2/TiO2Compound wet gel is prepared according to the following steps to obtain:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, obtains TiO2Colloidal sol；Esters of silicon acis and hydrochloric acid are in solvent
Middle mixing carries out hydrolysis, obtains SiO2Colloidal sol；
By the TiO2Colloidal sol, the SiO2Colloidal sol and formamide mixing, carry out aging, obtain SiO2/TiO2It is compound wet solidifying
Glue.
Preferably, the Al2O3Wet gel is prepared according to the following steps to obtain:
Hybrid reaction, reaction product are stood in a solvent for aluminium alcoholates and ethyl acetoacetate, obtain Al2O3Wet gel.
Compared with prior art, the present invention provides a kind of preparation methods of inorganic aerogels.Preparation provided by the invention
Method is heated to the temperature of setting the following steps are included: inorganic wet gel and dried medium are put into reaction kettle under confined conditions
Degree and pressure, constant temperature are kept, and are stopped heating and exhaust pressure relief later, are obtained inorganic aerogels；The dried medium include ethyl alcohol,
One of water, acetone and n-hexane are a variety of；The volume ratio of the inorganic wet gel and dried medium is 1:(0.5~10)；
The temperature set is 120~240 DEG C；The pressure set is 0.5~5.9MPa.Preparation method provided by the invention is logical
It crosses and the dry technical process of wet gel and condition is in optimized selection, in the case where not needing using overcritical equipment, both
It ensure that the quality of product, and substantially reduce the dry duration of wet gel.Preparation method provided by the invention enormously simplifies
The drying process of aeroge, it is low in cost and dry time-consuming short, it is suitble to push away in the large-scale industrial production of inorganic aerogels
It is wide to use.The results showed that there is biggish specific surface area and lower using the inorganic aerogels of the method for the present invention preparation
Density, cracking contraction is small, and transparency is high, there is preferable thermal stability.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
The embodiment of invention for those of ordinary skill in the art without creative efforts, can also basis
The attached drawing of offer obtains other attached drawings.
Fig. 1 is the pictorial diagram for the aerosil that embodiment 1 is prepared；
Fig. 2 is the TEM figure for the aerosil that embodiment 1 is prepared；
Fig. 3 is the SEM figure for the aerosil that embodiment 1 is prepared；
Fig. 4 is the isothermal nitrogen adsorption desorption curve figure for the aerosil calcining front and back that embodiment 1 is prepared；
Fig. 5 is the pore size distribution curve figure before and after the calcining for the aerosil that embodiment 1 is prepared.
Specific embodiment
The following is a clear and complete description of the technical scheme in the embodiments of the invention, it is clear that described embodiment
Only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, the common skill in this field
Art personnel every other embodiment obtained without making creative work belongs to the model that the present invention protects
It encloses.
The present invention provides a kind of preparation methods of inorganic aerogels, comprising the following steps:
Inorganic wet gel and dried medium are put into reaction kettle, are heated to the temperature and pressure of setting under confined conditions,
Constant temperature is kept, and is stopped heating and exhaust pressure relief later, is obtained inorganic aerogels；
The dried medium includes one of ethyl alcohol, water, acetone and n-hexane or a variety of；
The volume ratio of the inorganic wet gel and dried medium is 1:(0.5~10)；
The temperature set is 120~240 DEG C；
The pressure set is 0.5~5.9MPa.
In the present invention, inorganic wet gel and dried medium are put into reaction kettle first.Wherein, the inorganic wet gel
Including but not limited to SiO2Wet gel, TiO2Wet gel, SiO2/TiO2Compound wet gel and Al2O3One of wet gel is more
Kind.In one embodiment provided by the invention, the SiO2Wet gel is prepared according to the following steps to obtain:
Esters of silicon acis and hydrochloric acid mix in a solvent carries out hydrolysis, obtains hydrolysate；
The hydrolysate and the reaction of Ammonia material mixing, reaction product carry out aging, obtain SiO2Wet gel.
In the SiO that the above embodiment of the present invention provides2In the preparation step of wet gel, the esters of silicon acis is preferably positive silicic acid
Ethyl ester；The Ammonia substance preferably includes ammonium hydroxide and/or formamide；The solvent preferably includes second alcohol and water；The esters of silicon acis,
Ethyl alcohol, water, hydrochloric acid and ammonium hydroxide molar ratio be preferably 1:(2~4): (5~7): (3 × 10-3~5 × 10-3): (5 × 10-3~7
×10-3), concretely 1:3:6:4 × 10-3:6×10-3；The temperature of the hydrolysis is preferably 40~80 DEG C, concretely
40 DEG C, 45 DEG C, 50 DEG C, 55 DEG C, 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C or 80 DEG C；The time of the hydrolysis is preferably 0.5~
2h, concretely 0.5h, 1h, 1.5h or 2h；The temperature of the hybrid reaction is preferably 15~35 DEG C, concretely 15 DEG C, 20
DEG C, 25 DEG C (room temperature), 30 DEG C or 35 DEG C；The time of the hybrid reaction is preferably 10~60min, concretely 10min,
15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min；The temperature of the aging is excellent
15~35 DEG C are selected as, concretely 15 DEG C, 20 DEG C, 25 DEG C (room temperature), 30 DEG C or 35 DEG C；The time of the aging is preferably 6~
12h, concretely 6h, 7h, 8h, 9h, 10h, 11h or 12h.
In the SiO that the above embodiment of the present invention provides2, it is preferable to use ethyl alcohol obtains aging in the preparation step of wet gel
SiO2Wet gel carries out exchange of solvent, and the number of the exchange of solvent is preferably 2~3 times, each exchange of solvent when
Between preferably 8~12h.
In one embodiment provided by the invention, the TiO2Wet gel is prepared according to the following steps to obtain:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, and hydrolysate carries out aging, obtains TiO2Wet gel.
In the TiO that the above embodiment of the present invention provides2In the preparation step of wet gel, the titanate esters are preferably metatitanic acid fourth
Ester；The solvent preferably includes second alcohol and water；The titanate esters, ethyl alcohol, water and acetic acid molar ratio be preferably 1:(8~12):
(2~4): (1~3), concretely 1:10:3:2；The temperature of the aging is preferably 15~35 DEG C, concretely 15 DEG C, 20
DEG C, 25 DEG C (room temperature), 30 DEG C or 35 DEG C；The time of the aging is preferably 12~48h, concretely 12h, 15h, 18h, 21h,
For 24 hours, 27h, 30h, 33h, 36h, 39h, 42h, 45h or 48h.
In the TiO that the above embodiment of the present invention provides2, it is preferable to use ethyl alcohol obtains aging in the preparation step of wet gel
TiO2Wet gel carries out exchange of solvent, and the number of the exchange of solvent is preferably 2~3 times, each exchange of solvent when
Between preferably 8~12h.
In one embodiment provided by the invention, the SiO2/TiO2Compound wet gel is prepared according to the following steps
It arrives:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, obtains TiO2Colloidal sol；Esters of silicon acis and hydrochloric acid are in solvent
Middle mixing carries out hydrolysis, obtains SiO2Colloidal sol；
By the TiO2Colloidal sol, the SiO2Colloidal sol and formamide mixing, carry out aging, obtain SiO2/TiO2It is compound wet solidifying
Glue.
In the SiO that the above embodiment of the present invention provides2/TiO2In the preparation step of compound wet gel, TiO is prepared2Colloidal sol
When, the titanate esters are preferably butyl titanate；The solvent preferably includes second alcohol and water；The titanate esters, ethyl alcohol, water and acetic acid
Molar ratio be preferably 1:(8~12): (2~4): (1~3), concretely 1:10:3:2.
In the SiO that the above embodiment of the present invention provides2/TiO2In the preparation step of compound wet gel, SiO is prepared2Colloidal sol
When, the esters of silicon acis is preferably ethyl orthosilicate；The solvent preferably includes second alcohol and water；The esters of silicon acis, ethyl alcohol, water and salt
The molar ratio of acid is preferably 1:(2~4): (5~7): (3 × 10-3~5 × 10-3), concretely 1:3:6:4 × 10-3。
In the SiO that the above embodiment of the present invention provides2/TiO2In the preparation step of compound wet gel, the TiO2In colloidal sol
Ti and the SiO2The molar ratio of Si in colloidal sol is preferably (0.5~6): 1；The temperature of the aging is preferably 15~35
DEG C, concretely 15 DEG C, 20 DEG C, 25 DEG C (room temperature), 30 DEG C or 35 DEG C；The time of the aging is preferably 6~12h, specifically may be used
For 6h, 7h, 8h, 9h, 10h, 11h or 12h.
In the SiO that the above embodiment of the present invention provides2/TiO2, it is preferable to use ethyl alcohol pair in the preparation step of compound wet gel
The SiO that aging obtains2/TiO2Compound wet gel carries out exchange of solvent, and the number of the exchange of solvent is preferably 2~3 times, every time
The time of the exchange of solvent is preferably 8~12h.
In one embodiment provided by the invention, the Al2O3Wet gel is prepared according to the following steps to obtain:
Hybrid reaction, reaction product are stood in a solvent for aluminium alcoholates and ethyl acetoacetate, obtain Al2O3Wet gel.
In the Al that the above embodiment of the present invention provides2O3In the preparation step of wet gel, the aluminium alcoholates is preferably sec-butyl alcohol
Aluminium, the solvent preferably include second alcohol and water；The aluminium alcoholates, ethyl alcohol, water and ethyl acetoacetate molar ratio be preferably 1:(15
~25): (0.5~2): (0.1~0.3), concretely 1:20:1:0.2；The temperature of the hybrid reaction is preferably 40~80
DEG C, concretely 40 DEG C, 45 DEG C, 50 DEG C, 55 DEG C, 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C or 80 DEG C；The time of the hybrid reaction is excellent
It is selected as 30~60min, concretely 30min, 35min, 40min, 45min, 50min, 55min or 60min.
In the Al that the above embodiment of the present invention provides2O3, it is preferable to use ethyl alcohol and n-butanol pair in the preparation step of wet gel
Stand obtained Al2O3Wet gel carries out exchange of solvent, and the number of the exchange of solvent is preferably 2~3 times, each solvent
The time of exchange is preferably 8~12h.
In the present invention, the dried medium includes one of ethyl alcohol, water, acetone and n-hexane or a variety of；The nothing
The volume ratio of machine wet gel and dried medium is 1:(0.5~10), concretely 1:0.5,1:1,1:1.5,1:2,1:2.5,1:
3,1:3.5,1:4,1:4.5,1:5,1:5.5,1:6,1:6.5,1:7,1:7.5,1:8,1:8.5,1:9,1:9.5 or 1:10.
In the present invention, after inorganic wet gel and dried medium being put into, the reaction kettle is heated under confined conditions
The temperature and pressure of setting.Wherein, the heating rate of the heating is preferably 1~5 DEG C/min, concretely 1 DEG C/min, 1.5
DEG C/min, 2 DEG C/min, 2.5 DEG C/min, 3 DEG C/min, 3.5 DEG C/min, 4 DEG C/min, 4.5 DEG C/min or 5 DEG C/min；It is described to set
Fixed temperature be 120~240 DEG C, concretely 120 DEG C, 125 DEG C, 130 DEG C, 135 DEG C, 140 DEG C, 145 DEG C, 150 DEG C, 155 DEG C,
160℃、165℃、170℃、175℃、180℃、185℃、190℃、195℃、200℃、205℃、210℃、215℃、220
DEG C, 225 DEG C, 230 DEG C, 235 DEG C or 240 DEG C；The pressure set as 0.5~5.9MPa, concretely 0.5MPa, 1MPa,
1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa, 5.5MPa or 5.9MPa.
In the present invention, after being heated to the temperature and pressure of setting, constant temperature is kept.Wherein, the time that the constant temperature is kept
Preferably 1~3h, concretely 1h, 1.5h, 2h, 2.5h or 3h.
In the present invention, after constant temperature is kept, stop heating and exhaust pressure relief.Wherein, the rate of the exhaust pressure relief
Preferably 0.1~0.5MPa/min, concretely 0.1MPa/min, 0.15MPa/min, 0.2MPa/min, 0.25MPa/min,
0.3MPa/min, 0.35MPa/min, 0.4MPa/min, 0.45MPa/min or 0.5MPa/min.After exhaust pressure relief, obtain
Dried inorganic aerogels.
In the present invention, it is preferred to forced air drying be carried out to the inorganic aerogels obtained after exhaust pressure relief, to remove remnants'
Dried medium.Wherein, the temperature of the forced air drying is preferably 80~120 DEG C, concretely 80,85,90,95,100,105,
110,115 or 120；The time of the forced air drying is preferably 6~for 24 hours, concretely 6h, 9h, 12h, 15h, 18h, 21h or
24h。
Preparation method provided by the invention is by being in optimized selection the dry technical process of wet gel and condition, not
In the case where needing to use overcritical equipment, the quality of product not only ensure that, but also substantially reduce the dry duration of wet gel.This
The preparation method that invention provides enormously simplifies the drying process of aeroge, low in cost, and dry time-consuming short (about 2~6h),
It is suitble to promote the use of in the large-scale industrial production of inorganic aerogels.
The results showed that using the method for the present invention preparation inorganic aerogels pattern and have excellent performance, specifically include:
1) it is bulk, the solid forms of gel script, and excellent transparency is able to maintain, with SiO2For aeroge, it is seen that
Light transmission rate reaches 80~90%；
2) the inorganic aerogels specific surface area with higher using the method for the present invention preparation and relatively uniform aperture point
Cloth, specific surface area range is in 800~1000m2Between/g, pore diameter range between 10~20nm, density range 0.120~
0.420g/cm3Between；
3) there is relatively good thermal stability using the inorganic aerogels of the method for the present invention preparation, 900 DEG C of processing quality become
Change 8~13% or so, and specific surface area can reach 700~900m after 300~600 DEG C of calcinings2/g.Pore-size distribution becomes
It is preferable to change the aeroge skeleton structure for less showing to prepare using subcritical method.
For the sake of becoming apparent from, it is described in detail below by following embodiment.
Embodiment 1
Prepare SiO2Aeroge
Wet gel, ethyl orthosilicate (TEOS), dehydrated alcohol (Et-OH), deionization are prepared using soda acid two-step method first
Water (H2O), dilute hydrochloric acid (HCl), weak aqua ammonia (NH3.H2O) the mass ratio of the material is nTEOS: nEt-OH: nH2O: nHCl: nNH3.H2O=1:3:
6:4×10-3:6×10-3。
The ester alcohol and water of aforementioned proportion is uniformly mixed, heating water bath is adjusted to dilute hydrochloric acid (0.4mol/L) is added at 60 DEG C
Saving pH is 3~4, and stirring is fully hydrolyzed 1h in thermostat water bath.Continue stirring when being cooled to room temperature, dilute ammonia is added dropwise while stirring
It is 6~7 that water (0.4mol/L), which adjusts pH,.About 30min or so forms transparent gel rubber system.By the gel seal of generation in room temperature
Lower aging 8h is to enhance skeleton structure.Appropriate dehydrated alcohol is added later carries out exchange of solvent 2~3 times (8~12h every time),
The bigger water of surface tension in displacement inside gel and preferably further enhance skeleton structure.Wet gel is placed in instead
It answers in kettle, dehydrated alcohol (dehydrated alcohol is 9:1 with wet gel volume ratio) is added, sealing is warming up to the rate of 2 DEG C/min
220 DEG C, pressure is up to 3.5MPa, and fixed temperature stops heating after keeping 1.5h, with the rate exhaust pressure relief of 0.5MPa/min, to anti-
Sample is taken out after answering kettle to be cooled to room temperature, is placed in 100 DEG C of dry 12h in air dry oven, is removed remaining ethyl alcohol, is obtained airsetting
Glue.
The visible light transmittance of the aeroge is 89.4%, specific surface area 973.68m2/ g, pore-size distribution is on the left side 10nm
The right side is the more uniform spherolite aggregation of pore structure, density 0.221g/m3, the specific surface area after 600 DEG C of calcination processing 5h
Still reach 850.59m2/g.Pore-size distribution variation is less after calcining and pass does not change.
Aerosil manufactured in the present embodiment is observed and detected, as a result as shown in Fig. 1~5, Fig. 1 is real
Apply the pictorial diagram for the aerosil that example 1 is prepared；Fig. 2 is the aerosil that embodiment 1 is prepared
TEM figure；Fig. 3 is the SEM figure for the aerosil that embodiment 1 is prepared；Fig. 4 is the dioxy that embodiment 1 is prepared
The isothermal nitrogen adsorption desorption curve figure of SiClx aeroge calcining front and back；Fig. 5 is the silica airsetting that embodiment 1 is prepared
Pore size distribution curve figure before and after the calcining of glue.From figure 1 it appears that use the dry aeroge prepared of this method for
Light blue, transparency is higher.Fig. 2~3 can be seen that the microstructure of the aeroge using drying means preparation, be uniform
Contiguous network shape structure, skeleton particle distribution it is loose.It can be seen that the airsetting being prepared using this method in Fig. 4 and Fig. 5
Glue pore-size distribution is relatively uniform, and average pore size is all being distribution 10nm or so, and concentration is compared in distribution, forges by 600 DEG C of high temperature
After burning, pass structure and the pore-size distribution variation of aeroge less, illustrate the aeroge being prepared using seasoning heat
Stability is preferable.
Embodiment 2
Process flow is referring to embodiment 1, difference are as follows: weak aqua ammonia is changed to formamide in gel preparation course, molar ratio is not
Become.The visible light transmittance of aeroge obtained is 90%, specific surface area 993.56m2/ g, pore-size distribution in 10nm or so,
It more evenly compared to 1 pore-size distribution of case, is the more uniform spherolite aggregation of pore structure, density 0.201g/m3, by 600
Specific surface area still reaches 890.58m after DEG C calcination processing 5h2/g.Macroporous type does not change for pore-size distribution variation after calcining
Become.
Embodiment 3
Process flow is referring to embodiment 1, difference are as follows: 220 DEG C of holding 1.0h of constant temperature in autoclave.Aeroge obtained can
Light-exposed transmitance is 86.4%, specific surface area 960.28m2/ g, for pore-size distribution in 10nm or so, pore structure is size and arrangement
All relatively uniform spherolite aggregation, density 0.232g/m3, density still reaches after 600 DEG C of calcination processing 5h
835.93m2/g.Macroporous type does not change for pore-size distribution variation after calcining.
Embodiment 4
Process flow is referring to embodiment 1, difference are as follows: 220 DEG C of holding 2.0h of constant temperature in autoclave.Aeroge obtained can
Light-exposed transmitance is 88.3%, specific surface area 933.86m2/ g, pore-size distribution are the more uniform ball of pore structure in 10nm or so
Grain aggregation, density 0.198g/m3, specific surface area still reaches 820.36m after 600 DEG C of calcination processing 5h2/g.Calcining
Pore-size distribution and pass are constant later, and gel skeleton structure and arrangement mode are not affected.
Embodiment 5
Process flow is referring to embodiment 1, difference are as follows: 180 DEG C of holding 1.5h of constant temperature, corresponding pressure are in autoclave
1.0MPa.The visible light transmittance of aeroge obtained is 85.4%, specific surface area 969.84m2/ g, pore-size distribution is in 10nm
Left and right is the more uniform spherolite aggregation of pore structure, density 0.235g/m3, the specific surface after 600 DEG C of calcination processing 5h
Product still reaches 849.49m2/g.Pore-size distribution and pass are constant after calcining, and gel skeleton structure and arrangement mode are simultaneously not affected by
It influences.
Embodiment 6
Process flow is referring to embodiment 1, difference are as follows: 200 DEG C of holding 1.5h of constant temperature, corresponding pressure are in autoclave
2.5MPa.The visible light transmittance of aeroge obtained is 89.9%, specific surface area 874.63m2/ g, pore-size distribution is in 10nm
Left and right is the more uniform spherolite aggregation of pore structure, density 0.210g/m3, the specific surface after 600 DEG C of calcination processing 5h
Product still reaches 833.56m2/g.Pore-size distribution and pass are constant after calcining, and gel skeleton structure and arrangement mode are simultaneously not affected by
It influences.
Embodiment 7
Process flow is referring to embodiment 1, difference are as follows: 240 DEG C of holding 1.5h of constant temperature, corresponding pressure are in autoclave
5.0MPa.The visible light transmittance of aeroge obtained is 78.6%, specific surface area 925.90m2/ g, pore-size distribution is in 10nm
Left and right is the more uniform spherolite aggregation of pore structure, density 0.228g/m3, the specific surface after 600 DEG C of calcination processing 5h
Product still reaches 890.23m2/g.Pore-size distribution and pass are constant after calcining, and gel skeleton structure and arrangement mode are simultaneously not affected by
It influences.
Embodiment 8
Prepare TiO2Aeroge
A certain amount of butyl titanate (TnBT) is uniformly mixed to obtain solution A with suitable dehydrated alcohol (Et-OH)；By vinegar
Acid (HAC), secondary distilled water (H2O) and equivalent dehydrated alcohol is uniformly mixed and obtains solution B.Under vigorous stirring, by solution B by
It is added dropwise in solution A, butyl titanate hydrolyzes to obtain TiO2Colloidal sol.Room temperature after the sealing of this colloidal sol is aged natural gel-forming for 24 hours
TiO2Wet gel.
Wherein, nTnBT: nEt-OH: nH2O: nHAC=1:10:3:2.Appropriate dehydrated alcohol is added later carries out exchange of solvent 2
~3 times (8~12h every time), the bigger water of surface tension in displacement inside gel and preferably further enhance skeleton
Structure.Wet gel is placed in reaction kettle, dehydrated alcohol (dehydrated alcohol is 9:1 with wet gel volume ratio), sealing, with 2 is added
DEG C/rate of min is warming up to 220 DEG C, pressure is up to 3.5MPa, and fixed temperature stops heating after keeping 1.5h, with 0.5MPa/min
Rate exhaust pressure relief, take out sample after reaction kettle is cooled to room temperature, be placed in 100 DEG C of dry 12h in air dry oven, remove
Remaining ethyl alcohol, obtains TiO2Aeroge.Temperature lower calcination 6h by obtained aeroge at 600 DEG C.Obtain Detitanium-ore-type
TiO2Aeroge.
Embodiment 9
Prepare SiO2/TiO2Aeroge
A certain amount of butyl titanate (TnBT) is uniformly mixed to obtain solution A with suitable dehydrated alcohol (Et-OH)；By vinegar
Acid (HAC), secondary distilled water (H2O) and equivalent dehydrated alcohol (Et-OH) is uniformly mixed and obtains solution B.Under vigorous stirring, will
Solution B is added dropwise in solution A, and butyl titanate hydrolyzes to obtain TiO2Colloidal sol.Wherein, nTnBT: nEt-OH: nH2O: nHAC=1:10:3:
2.Meanwhile according to nTEOS: nEt-OH: nH2O: nHCl=1:3:6:4 × 10-3Ratio prepares SiO2Colloidal sol, hydrolysis is completely molten
TiO is added after glue is cooling21.5mL formamide is added in colloidal sol, is sufficiently stirred and is placed under room temperature natural gel.By generation
Gel seal at room temperature aging 8h to enhance skeleton structure.Appropriate dehydrated alcohol is added later to carry out exchange of solvent 2~3 times
(8~12h every time), the bigger water of surface tension in displacement inside gel and preferably further enhances skeleton structure.
Then according to the drying means in case study on implementation 8 to SiO2/TiO2Wet gel is dried, and control Si:Ti molar ratio is 1:
(0.5~6) obtains the composite aerogel of different proportion.Anatase crystal structure, specific surface is presented after 600 DEG C of calcinings
Product range is in 264.79~680.61m2Between/g, pore-size distribution is in 2~5nm or so.
Embodiment 10
Prepare Al2O3Aeroge
With aluminium secondary butylate (ASB), ethyl alcohol (Et-OH), water (H2O), ethyl acetoacetate (AIP) is raw material, molar ratio
For nASB: nEt-OH: nH2O: nAIP=1:20:1:0.2, reaction temperature are to stir 45 minutes under 60 degrees Celsius, are then allowed to stand natural shape
At wet gel.It adds dehydrated alcohol and n-butanol mixed liquor carries out solvent and replaces 2~3 times (8~12h every time).By wet gel
It is placed in reaction kettle, dehydrated alcohol (dehydrated alcohol is 9:1 with wet gel volume ratio), sealing, with the rate liter of 2 DEG C/min is added
For temperature to 220 DEG C, pressure is up to 3.5MPa, and fixed temperature stops heating after keeping 1.5h, with the rate exhaust pressure relief of 0.5MPa/min,
Sample is taken out after reaction kettle is cooled to room temperature, is placed in 100 DEG C of dry 12h in air dry oven, remaining ethyl alcohol is removed, obtains
Al2O3Aeroge.The Al being prepared known to after tested using this method2O3Aeroge specific surface area 651.23~
925.87m2Between/g, Kong Rong is in 1.5~2.3cm3Between/g.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (10)
1. a kind of preparation method of inorganic aerogels, comprising the following steps:
Inorganic wet gel and dried medium are put into reaction kettle, are heated to the temperature and pressure of setting, constant temperature under confined conditions
It keeps, stops heating and exhaust pressure relief later, obtain inorganic aerogels；
The dried medium includes one of ethyl alcohol, water, acetone and n-hexane or a variety of；
The volume ratio of the inorganic wet gel and dried medium is 1:(0.5~10)；
The temperature set is 120~240 DEG C；
The pressure set is 0.5~5.9MPa.
2. preparation method according to claim 1, which is characterized in that the heating rate of the heating is 1~5 DEG C/min.
3. preparation method according to claim 1, which is characterized in that the time that the constant temperature is kept is 1~3h.
4. preparation method according to claim 1, which is characterized in that the rate of the exhaust pressure relief is 0.1~0.5MPa/
min。
5. preparation method according to claim 1, which is characterized in that further include: the product after exhaust pressure relief is roused
It air-dries dry.
6. preparation method according to claim 1, which is characterized in that the inorganic wet gel includes SiO2Wet gel, TiO2
Wet gel, SiO2/TiO2Compound wet gel and Al2O3One of wet gel is a variety of.
7. preparation method according to claim 6, which is characterized in that the SiO2Wet gel is prepared according to the following steps
It arrives:
Esters of silicon acis and hydrochloric acid mix in a solvent carries out hydrolysis, obtains hydrolysate；
The hydrolysate and the reaction of Ammonia material mixing, reaction product carry out aging, obtain SiO2Wet gel.
8. preparation method according to claim 6, which is characterized in that the TiO2Wet gel is prepared according to the following steps
It arrives:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, and hydrolysate carries out aging, obtains TiO2Wet gel.
9. preparation method according to claim 6, which is characterized in that the SiO2/TiO2Compound wet gel is according to following step
Suddenly it is prepared:
Titanate esters and acetic acid mix in a solvent carries out hydrolysis, obtains TiO2Colloidal sol；Esters of silicon acis and hydrochloric acid mix in a solvent
Reaction is hydrolyzed, obtains SiO2Colloidal sol；
By the TiO2Colloidal sol, the SiO2Colloidal sol and formamide mixing, carry out aging, obtain SiO2/TiO2Compound wet gel.
10. preparation method according to claim 6, which is characterized in that the Al2O3Wet gel is prepared according to the following steps
It obtains:
Hybrid reaction, reaction product are stood in a solvent for aluminium alcoholates and ethyl acetoacetate, obtain Al2O3Wet gel.
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