CN100574863C - TiO 2-SiO 2Composite aerogel and preparation method thereof - Google Patents

Abstract

The invention provides a kind of TiO ₂-SiO ₂Composite aerogel and preparation method thereof.This TiO ₂-SiO ₂The Ti/Si mol ratio of composite aerogel 1: 10～10: 1, density are 0.1～0.35g/cm ³, porosity 84～94%, aperture 5.0～20.0nm, pore volume be 1.0～5.0cm ³/ g, specific area are 500～1200m ²/ g.Its preparation method comprises that mainly modifier that use is made up of alcohols, organosilicon alkanes and alkanes reagent carries out modification and solvent is replaced the step of handling.TiO of the present invention ₂-SiO ₂Composite aerogel has that density is low, specific area is big, high pore volume, high porosity characteristics, and porosity can reach 84～94%; TiO of the present invention ₂-SiO ₂The preparation method of composite aerogel adopts raw material TiCl cheap and easy to get ₄With industry water glass, can reduce production costs, and constant pressure and dry technology is convenient and easy, be suitable for large-scale industrial production and application.

Description

TiO 2-SiO 2Composite aerogel and preparation method thereof

Technical field

The present invention relates to high pore volume, high-specific surface area TiO ₂-SiO ₂The constant pressure and dry preparation method of composite aerogel.

Background technology

Titanium dioxide (TiO ₂) advantage such as catalysis material has that oxidability is strong, photocatalytic activity is high, chemistry and optical stability are good, have a wide range of applications in environmental protection fields such as solar cell and organic pollution processing, sterilizings.Particularly in recent years, nano-TiO ₂Research in environmental protection fields such as air cleaning, water purification is subject to people's attention day by day with application.The same with other catalysis material, TiO ₂Catalysis material needs big specific area; In addition, loose structure can give material high suction-operated, and absorption/photocatalysis synergy can effectively be eliminated the organic pollution in air, the water.SiO ₂Aeroge is a kind of novel light nano-porous materials, has characteristics such as high-specific surface area, high porosity.Therefore prepare TiO ₂-SiO ₂Composite aerogel is expected in conjunction with TiO ₂Photocatalytic activity, the high adsorption and the SiO of porous material ₂High thermal stability and good mechanical performance, will have very application prospects relating to absorption/light-catalysed many fields.

For obtaining the TiO of loose structure ₂-SiO ₂Composite aerogel, adopting more method in the past is to adopt the supercritical drying drying process, employing sol-gel processes such as B.Malinowska have prepared TiO by Supercritical Drying Technology ₂-SiO ₂Composite aerogel, gained aeroge specific area is 320～327m ²/ g (Applied Catalysis B:Environmental, 2003,46:441-451).Yet the supercritical drying arts demand is used autoclave, complex process, cost height, and certain danger is arranged.In recent years, adopted the non-supercritical drying process to prepare SiO ₂Aeroge, TiO ₂-SiO ₂The research of aeroge receives much attention.With industry water glass is raw material, adopts constant pressure and dry technology can prepare the SiO of high porosity ₂Aeroge (Materials Letters, 2006,60:3718-3722; Silicate journal, 2005,33 (8): 963-967).With butyl titanate, Ludox is raw material, by adding dry control chemical addition agent formamide to form fairly perfect gel network structure, replace and classification ageing and drying and other steps by alcohol solution dipping, the low surface tension solvent of wet gel being carried out ethyl orthosilicate, can realize block TiO ₂-SiO ₂The dry preparation of the non-supercritical of composite aerogel; Gained TiO ₂-SiO ₂About 0.4～the 0.9g/cm of aeroge apparent density ³, porosity is about 80%～95%, specific area 300～400m ²/ g, pore volume is at 1～2cm ³(SCI, 2004,25 (2): 325-329 between the/g; Tongji University's journal (natural science edition), 2005,33 (8): 1078-1082), this technology is owing to be to adopt the ethanol solution of low surface tension to soak gel repeatedly to replace the water in the gel, therefore very consuming time, and have the halfway shortcoming of replacement, so gained TiO ₂-SiO ₂The pore volume of aeroge and specific area are not very high.In addition, adopt expensive titanium alkoxide of price and silicon alkoxide as preparation TiO ₂-SiO ₂The presoma of aeroge, preparation cost are higher relatively, are unfavorable for TiO ₂-SiO ₂The large-scale production of aeroge.

Summary of the invention

The object of the present invention is to provide a kind of TiO of high pore volume ₂-SiO ₂Composite aerogel, and the method for utilizing the constant pressure and dry technology to prepare this composite aerogel is provided.

TiO of the present invention ₂-SiO ₂The Ti/Si mol ratio of composite aerogel 1: 10～10: 1, density are 0.1～0.35g/cm ³, porosity 84～94%, aperture 5.0～20.0nm, pore volume be 1.0～5.0cm ³/ g, specific area are 500～1200m ²/ g.

This TiO ₂-SiO ₂The preparation method of composite aerogel comprises the steps:

1. prepare TiCl respectively ₄The aqueous solution and silicate solution;

2. prepare TiO ₂-SiO ₂Complex sol, making the Ti/Si mol ratio is 1: 10～10: 1;

3. colloidal sol ageing forms plural gel;

4. plural gel is carried out modification and solvent replacement processing, modifier is made up of alcohols, organosilicon alkanes and alkanes reagent; Use the wet gel after alkanes reagent cleans modification after finishing;

Alcohols wherein is selected from ethanol or isopropyl alcohol, and the organosilicon alkanes is selected from trim,ethylchlorosilane or MTES, and the alkane in the modifier is selected from n-hexane, cyclohexane or heptane;

5. the gel after modification being handled carries out constant pressure and dry to be handled, and obtains TiO ₂-SiO ₂Composite aerogel.

Wherein, the volume ratio of alcohols and organosilicon alkanes reagent is 1: 1～1: 1.5 in the described step modifier 4..

Alkanes reagent in the modifier uses mainly as solvent, should not have gel piece at least fully.The present inventor generally selects to control the organosilicon alkanes reagent in the modifier and the volume ratio 1: 5～10 of alkanes reagent, but its amount ratio is more flexible, can the modification of gel and solvent replacement degree be controlled by the control processing time.The standard that processing should reach is: gel piece is Transparent color or white, and is floating state at aqueous phase.

And being used to clean the alkanes reagent of gel in 4., step is selected from n-hexane, cyclohexane or heptane.

TiO of the present invention ₂-SiO ₂Step described in the preparation method of composite aerogel 5., promptly the concrete operation method of gel drying is: heat preservation and dryness 2h or successively at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h under 120～150 ℃ of conditions.

The compound method of mesosilicic acid solution of the present invention is:

(a) the industry water glass of modulus=3.38 is pressed V with deionized water _{Industry water glass}: V _{Deionized water}=1: 4 dilution proportion;

(b) carry out ion-exchange with strongly acidic styrene's cationic ion-exchange resin, get the silicate solution of pH=2～3.

2. step described in the present invention prepares TiO ₂-SiO ₂The concrete grammar of complex sol is: stir on one side, on one side with TiCl ₄The aqueous solution slowly is added drop-wise in the silicic acid, stirs 1h.

Method to the invention described above is further described, and more specifically, this method should comprise following operating procedure:

1. prepare TiCl respectively ₄The aqueous solution and silicate solution;

TiCl ₄The preparation of the aqueous solution: according to the TiCl that will prepare ₄The concentration of the aqueous solution, accurately required ice cube of weighing and TiCl ₄, with TiCl ₄Drip to lentamente on the ice cube, treat that ice cube melts fully after, fully stir 1h, this operates in the fume hood and finishes, the TiCl that obtains ₄After the removal of impurities of aqueous solution suction filtration, sealing is preserved in dark-brown vial;

The preparation of silicate solution: the industry water glass of modulus=3.38 is pressed V with deionized water _{Industry water glass}: V _{Deionized water}=1: 4 dilution proportion are carried out ion-exchange with strongly acidic styrene's cationic ion-exchange resin then, get the silicate solution of pH=2～3;

2. prepare TiO ₂-SiO ₂Complex sol: stir on one side, on one side with TiCl ₄The aqueous solution slowly is added drop-wise in the silicic acid, stirs 1h, and making the Ti/Si mol ratio is 1: 10～10: 1;

3. colloidal sol ageing in 14～80 ℃ water-bath forms plural gel;

4. the modification and the solvent of plural gel are replaced processing: modifier is made up of alcohols, organosilicon alkanes and alkanes reagent, alcohols in the modifier is selected from ethanol or isopropyl alcohol, the organosilicon alkanes is selected from trim,ethylchlorosilane or MTES, alkane is selected from n-hexane, cyclohexane or heptane, alcohols and organosilicon alkanes reagent volume be than 1: 1～1: 1.5, modification processing time 24～72h; Wet gel after finishing after usefulness n-hexane, cyclohexane or the washed with heptane modification;

5. the gel after modification being handled carries out constant pressure and dry to be handled, and promptly heat preservation and dryness 2h or successively at 60 ℃, 80 ℃, 120 ℃, 150 ℃ each heat preservation and dryness 2h down under 120～150 ℃ of conditions obtains TiO ₂-SiO ₂Composite aerogel.

TiO of the present invention ₂-SiO ₂Composite aerogel possesses good absorption property and photocatalytic degradation performance simultaneously, and absorption/photocatalysis synergy is also mutually promoted, and can effectively eliminate the pollutant in air, the water; And this composite aerogel has, and density is low, specific area is big, high pore volume, high porosity characteristics, and porosity can reach 84～94%; In addition, this composite aerogel also has excellent hydrophobicity, and water absorption rate is almost nil, is particularly suitable for absorption degradation oiliness organic pollution; After 500～550 ℃ of heat treatment, can change hydrophily into, can adsorb and photocatalytic degradation waste water in aqueous stain such as methyl orange, rhodamine B etc.

TiO of the present invention ₂-SiO ₂The preparation method of composite aerogel adopts raw material TiCl cheap and easy to get ₄With industry water glass, can reduce production costs, and constant pressure and dry technology is convenient and easy, be suitable for large-scale industrial production and application.

The specific embodiment

Mode with specific embodiment is further described technical scheme of the present invention below, the content that does not limit the present invention in any way.Among the following embodiment, if no special instructions, to the TiO that makes ₂-SiO ₂In the mensuration of composite aerogel particular product performance parameters:

(1) adopt the paraffin package method aeroge density (ρ) to be measured (discussion of light granular material bulk density detection method, " refractory material ", 2006,40 (2) 143～144.); Calculate porosity by the gained density data, it is as follows that porosity is calculated formula:

Wherein, ρ _SiO2=2.19g/cm ³

(2) utilize Quantachrome Instruments specific area and aperture analyzer to measure TiO ₂-SiO ₂The specific area of aeroge, pore volume and aperture, adsorbed gas are N ₂, pore volume calculates according to the BJH method, and the aperture is an average pore diameter;

(3) carry out TiO by absorption and photocatalytic degradation rhodamine B ₂-SiO ₂The absorption of composite aerogel/photocatalytic degradation performance test: with the TiO of 0.277g after 550 ℃ of heat treatment ₂-SiO ₂It is 10 that the aeroge sample is put into 30ml rhodamine B concentration ^-4In the aqueous solution of mol/L, having or not the variation of measuring solution absorbance under the high voltage mercury lamp radiation with spectrophotometer method, monitor TiO respectively with this ₂-SiO ₂Aeroge is to adsorption process and the photocatalytic degradation process of rhodamine B, and the absorbance of different adsorption times and light application time adopts UV751GD type ultraviolet/visible spectrophotometer to measure, and absorbing wavelength is 554nm.The computing formula of adsorption rate and photodissociation rate is as follows:

$\mathrm{\η}=(1-\frac{A}{A_0})\×100\%$

In the formula: A ₀The absorbance that-solution is initial; The absorbance of different absorption of A-and light application time; η-adsorption rate/photodissociation rate.

Embodiment 1

The TiO of preparation Ti/Si (mol ratio)=2: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution:

With the titanium tetrachloride is the titanium source, in fume hood the 50g ice cube is put into large beaker, and the 25.4ml titanium tetrachloride is added drop-wise on the ice cube lentamente, treat that ice cube melts fully after, fully stir 1h, with the TiCl that obtains ₄After the removal of impurities of aqueous solution suction filtration, obtain the TiCl that concentration is 3mol/L ₄The aqueous solution;

Get 10ml industry water glass (modulus=3.38, ^mSiO ₂%=26%, ρ=1.37g/ml) mix with the 40ml deionized water, ion-exchange is carried out by strongly acidic styrene's cationic ion-exchange resin in the back that stirs, and obtains the silicic acid of pH=2～3;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 8ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=2: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel to get final product, and absolute ethyl alcohol and trim,ethylchlorosilane volume ratio are 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=2: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.25g/cm ³, porosity is 89%, the aperture is 12.14nm, specific area 716.8m ²/ g, pore volume are 2.19cm ³/ g; 20 hours adsorption rate of this sample is 83% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 90% under illumination.

Embodiment 2

The TiO of preparation Ti/Si (mol ratio)=1: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 4ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=1: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel to get final product, and absolute ethyl alcohol and trim,ethylchlorosilane volume ratio are 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=1: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.21g/cm ³, porosity is 90%, the aperture is 10.59nm, specific area 763.2m ²/ g, pore volume are 2.12cm ³/ g; 20 hours adsorption rate of this sample is 69% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 82% under illumination.

Embodiment 3

The TiO of preparation Ti/Si (mol ratio)=3: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 12mlTiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=3: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel to get final product, and absolute ethyl alcohol and trim,ethylchlorosilane volume ratio are 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=3: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.31g/cm ³, porosity is 86%, the aperture is 12.74nm, specific area 684.9m ²/ g, pore volume are 2.28cm ³/ g; 20 hours adsorption rate of this sample is 90% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 92% under illumination.

Embodiment 4

The TiO of preparation Ti/Si (mol ratio)=1: 2 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 2ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=1: 2 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel to get final product, and absolute ethyl alcohol and trim,ethylchlorosilane volume ratio are 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=1: 2 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.17g/cm ³, porosity is 92%, the aperture is 8.77nm, specific area 802.7m ²/ g, pore volume are 2.07cm ³/ g; 20 hours adsorption rate of this sample is 77% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 94% under illumination.

Embodiment 5

The TiO of preparation Ti/Si (mol ratio)=1: 3 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 1.333mlTiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=1: 3 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel to get final product, and absolute ethyl alcohol and trim,ethylchlorosilane volume ratio are 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=1: 3 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.14g/cm ³, porosity is 94%, the aperture is 9.46nm, specific area 798.3m ²/ g, pore volume are 1.72cm ³/ g; 20 hours adsorption rate of this sample is 85% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 75% under illumination.

Embodiment 6

The TiO of preparation Ti/Si (mol ratio)=2: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 8ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=2: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of isopropyl alcohol, heptane and trim,ethylchlorosilane, and the heptane consumption did not have gel piece to get final product, and the volume ratio of isopropyl alcohol and trim,ethylchlorosilane is 1: 1;

C. the wet gel after the washed with heptane modification, the heptane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=2: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.28g/cm ³, porosity is 87%, the aperture is 12.93nm, specific area 691.3m ²/ g, pore volume are 2.23cm ³/ g; 20 hours adsorption rate of this sample is 85% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 91% under illumination.

Embodiment 7

The TiO of preparation Ti/Si (mol ratio)=1: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 4ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=1: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, change a modification liquid every 24h, modifier is made up of absolute ethyl alcohol, cyclohexane and MTES, and the cyclohexane consumption did not have gel piece to get final product, and the volume ratio of absolute ethyl alcohol and MTES is 1: 1.5;

C. the wet gel after the cyclohexane modification, the cyclohexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=1: 1 at 120 ℃ of heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.32g/cm ³, porosity is 85%, the aperture is 9.78nm, specific area 652.8m ²/ g, pore volume are 1.69cm ³/ g; 20 hours adsorption rate of this sample is 66% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 80% under illumination.

Embodiment 8

The TiO of preparation Ti/Si (mol ratio)=3: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Regulate the pH=6 of gained silicic acid with the NaOH aqueous solution of 1.0mol/L, under the magnetic agitation with 12mlTiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=3: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured cylindrical capsule into and is built in ageing in 60 ℃ of water-baths, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel room temperature;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of isopropyl alcohol, heptane and MTES, forms at 1: 1.5 according to volume ratio;

C. the wet gel after the washed with heptane modification, the heptane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=3: 1 at 150 ℃ of following heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.35g/cm ³, porosity is 84%, the aperture is 9.42nm, specific area 540m ²/ g, pore volume are 1.58cm ³/ g; 20 hours adsorption rate of this sample is 81% under no high voltage mercury lamp radiation, and 10 hours absorption-photodissociation rate is 86% under illumination.

Embodiment 9

The TiO of preparation Ti/Si (mol ratio)=1: 10 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Under the magnetic agitation with 2ml TiCl ₄The aqueous solution slowly is added drop-wise in the 50ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=1: 10 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured ageing at room temperature in the cylindrical capsule into, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel, and the volume ratio of absolute ethyl alcohol and trim,ethylchlorosilane is 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=1: 10 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.17g/cm ³, porosity is 92%, the aperture is 5.99nm, specific area 1110m ²/ g, pore volume are 1.66cm ³/ g; 25 hours adsorption rate of this sample is 79% under no high voltage mercury lamp radiation, and 25 hours absorption-photodissociation rate is 98% under illumination.

Embodiment 10

The TiO of preparation Ti/Si (mol ratio)=6: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Under the magnetic agitation with 24ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=6: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured ageing under 80 ℃ of water-baths in the cylindrical capsule into, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel, and the volume ratio of absolute ethyl alcohol and trim,ethylchlorosilane is 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=6: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.21g/cm ³, porosity is 90%, the aperture is 17.34nm, specific area 746.7m ²/ g, pore volume are 3.24cm ³/ g; 20 hours adsorption rate of this sample is 95.6% under no high voltage mercury lamp radiation, and 20 hours absorption-photodissociation rate is 96.5% under illumination.

Embodiment 11

The TiO of preparation Ti/Si (mol ratio)=4: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Under the magnetic agitation with 16ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=4: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured ageing at room temperature in the cylindrical capsule into, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel, and the volume ratio of absolute ethyl alcohol and trim,ethylchlorosilane is 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=4: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.18g/cm ³, porosity is 92%, the aperture is 18.58nm, specific area 1067m ²/ g, pore volume are 4.96cm ³/ g; 20 hours adsorption rate of this sample is 93.6% under no high voltage mercury lamp radiation, and 20 hours absorption-photodissociation rate is 88.6% under illumination.

Embodiment 12

The TiO of preparation Ti/Si (mol ratio)=10: 1 ₂-SiO ₂Composite aerogel:

1. prepare TiCl ₄The aqueous solution and silicate solution: 1. with embodiment 1 step;

2. prepare TiO ₂-SiO ₂Complex sol

Under the magnetic agitation with 40ml TiCl ₄The aqueous solution slowly is added drop-wise in the 10ml silicic acid, stirs 1h, can obtain the TiO of Ti/Si (mol ratio)=10: 1 ₂-SiO ₂Complex sol;

3. colloidal sol ageing forms plural gel;

With TiO ₂-SiO ₂Colloidal sol is poured ageing at room temperature in the cylindrical capsule into, forms block gel after the gelling;

4. the modification and the solvent of plural gel are replaced processing:

A. the still aging 24h of plural gel;

B. modifier is handled plural gel 72h, changes a modification liquid every 24h, and modifier is made up of absolute ethyl alcohol, n-hexane and trim,ethylchlorosilane, and the n-hexane consumption did not have gel, and the volume ratio of absolute ethyl alcohol and trim,ethylchlorosilane is 1: 1.5;

C. n-hexane cleans the wet gel after the modification, and the n-hexane consumption did not have gel to get final product;

5. the gel after the above-mentioned processing is put into thermostatic drying chamber,, make the block TiO of Ti/Si (mol ratio)=10: 1 at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h ₂-SiO ₂Composite aerogel.

After measured, this TiO ₂-SiO ₂The density of composite aerogel is 0.2g/cm ³, porosity is 91%, the aperture is 16.42nm, specific area 556.3m ²/ g, pore volume are 2.28cm ³/ g; 25 hours adsorption rate of this sample is 84.6% under no high voltage mercury lamp radiation, and 25 hours absorption-photodissociation rate is 93.5% under illumination.

Claims (8)

1.TiO ₂-SiO ₂Composite aerogel is characterized in that Ti/Si mol ratio 1: 10～10: 1, the density of described aeroge is 0.1～0.35g/cm ³, porosity 84～94%, aperture 5.0～20.0nm, pore volume be 1.0～5.0cm ³/ g, specific area are 500～1200m ²/ g.

2. the described TiO of claim 1 ₂-SiO ₂The preparation method of composite aerogel is characterized in that this method comprises the steps:

1. prepare TiCl respectively ₄The aqueous solution and silicate solution;

2. prepare TiO ₂-SiO ₂Complex sol, making the Ti/Si mol ratio is 1: 10～10: 1;

3. colloidal sol ageing forms plural gel;

4. plural gel is carried out modification and solvent replacement processing, modifier is made up of alcohols, organosilicon alkanes and alkanes reagent, uses the wet gel after alkanes reagent cleans modification after finishing;

Alcohols wherein is selected from ethanol or isopropyl alcohol, and the organosilicon alkanes is selected from trim,ethylchlorosilane or MTES, and the alkane in the modifier is selected from n-hexane, cyclohexane or heptane;

5. the gel after modification being handled carries out constant pressure and dry to be handled, and obtains TiO ₂-SiO ₂Composite aerogel.

3. TiO according to claim 2 ₂-SiO ₂The preparation method of composite aerogel is characterized in that the volume ratio of alcohols and organosilicon alkanes reagent is 1: 1～1: 1.5 in the described step modifier 4..

4. according to claim 2 or 3 described TiO ₂-SiO ₂The preparation method of composite aerogel, the alkanes reagent that it is characterized in that being used to during described step 4. cleaning gel is selected from n-hexane, cyclohexane or heptane.

5. according to claim 2 or 3 described TiO ₂-SiO ₂The preparation method of composite aerogel is characterized in that described step concrete operation method 5. is: heat preservation and dryness 2h or successively at 60 ℃, 80 ℃, 120 ℃, 150 ℃ following each heat preservation and dryness 2h under 120～150 ℃ of conditions.

6. TiO according to claim 2 ₂-SiO ₂The preparation method of composite aerogel, it is characterized in that described step 1. the compound method of mesosilicic acid solution be:

(a) the industry water glass of modulus=3.38 is pressed V with deionized water _{Industry water glass}: V _{Deionized water}=1: 4 dilution proportion;

(b) carry out ion-exchange with strongly acidic styrene's cationic ion-exchange resin, get the silicate solution of pH=2～3.

7. TiO according to claim 2 ₂-SiO ₂The preparation method of composite aerogel is characterized in that 2. described step prepares TiO ₂-SiO ₂The concrete grammar of complex sol is: stir on one side, on one side with TiCl ₄The aqueous solution slowly is added drop-wise in the silicic acid, stirs 1h.

8. TiO according to claim 2 ₂-SiO ₂The preparation method of composite aerogel is characterized in that this method specifically comprises following operating procedure:

1. prepare TiCl respectively ₄The aqueous solution and silicate solution;

TiCl ₄The preparation of the aqueous solution: according to the TiCl that will prepare ₄The concentration of the aqueous solution, accurately required ice cube of weighing and TiCl ₄, with TiCl ₄Drip to lentamente on the ice cube, treat that ice cube melts fully after, fully stir 1h, this operates in the fume hood and finishes, the TiCl that obtains ₄After the removal of impurities of aqueous solution suction filtration, sealing is preserved in dark-brown vial;

The preparation of silicate solution: the industry water glass of modulus=3.38 is pressed V with deionized water _{Industry water glass}: V _{Deionized water}=1: 4 dilution proportion are carried out ion-exchange with strongly acidic styrene's cationic ion-exchange resin then, get the silicate solution of pH=2～3;

2. prepare TiO ₂-SiO ₂Complex sol: stir on one side, on one side with TiCl ₄The aqueous solution slowly is added drop-wise in the silicic acid, stirs 1h, and making the Ti/Si mol ratio is 1: 10～10: 1;

3. colloidal sol ageing in 14～80 ℃ water-bath forms plural gel;

4. the modification and the solvent of plural gel are replaced processing: modifier is made up of alcohols, organosilicon alkanes and alkanes reagent, alcohols in the modifier is selected from ethanol or isopropyl alcohol, the organosilicon alkanes is selected from trim,ethylchlorosilane or MTES, alkane is selected from n-hexane, cyclohexane or heptane, alcohols and organosilicon alkanes reagent volume be than 1: 1～1: 1.5, modification processing time 24～72h; Wet gel after finishing after usefulness n-hexane, cyclohexane or the washed with heptane modification;

5. the gel after modification being handled carries out constant pressure and dry to be handled, and promptly heat preservation and dryness 2h or successively at 60 ℃, 80 ℃, 120 ℃, 150 ℃ each heat preservation and dryness 2h down under 120～150 ℃ of conditions obtains TiO ₂-SiO ₂Composite aerogel.