A kind of method for preparing TiO 2 sol by titanium tetrachloride
The present invention relates to the preparation of the preparation of nano material, particularly nano titanium oxide.
Nano-TiO
2Be a kind of catalysis that is widely used in, absorption, transmitter, makeup, sensitive materials, ceramic additive, the high function fine inorganic material in fields such as electronic engineering, especially TiO
2The film coating material have prior using value in these fields.At present, synthesis of nano TiO
2Method mainly be traditional sol-gel method (sol~gel) and vapor phase process (CVD).Utilizing the hydrolysis of metal alkoxide and the sol-gel method of polycondensation is a kind of effective ways that prepare nano material, has synthesized the TiO of size-grade distribution homogeneous
2Colloidal sol and nano-TiO
2Powder, but metal alkoxide costs an arm and a leg, toxicity is big, and facile hydrolysis is inflammable, is unfavorable for scale operation.And the CVD rule requires height aspect technology and material, complex process, and investment is big.Therefore, develop a kind of with low costly, simple to operate, be easy to the TiO of scale operation
2The preparation method of colloidal sol is very necessary, and it more helps further developing nano-TiO
2Material and relevant TiO
2Material elements.
The object of the present invention is to provide a kind of preparation method of TiO 2 sol, this method cost of material is cheap, prepared colloidal sol is stable, little and the homogeneous of granularity, in the properties of colloidal sol and formed material thereof and traditional by the colloidal sol of metal alkoxide preparation and the similar performance of respective material, and simple to operate, be easy to scale operation.
The invention provides and a kind ofly prepare TiO 2 sol, it is characterized in that: with TiCl by titanium tetrachloride
4Be raw material, generate precipitation with the alkaline solution effect, pH=6~7, this precipitation adds entry and acid solution after washing, add the acid amount and be [H
+]/[Ti] mol ratio is 0.2~1.0, stirs down at 0~90 ℃, dispergation obtained stable TiO after 12~60 hours
2Colloidal sol.
The alkaline solution that adopts in preparation method of the present invention is selected from ammoniacal liquor, urea, and NaOH, KOH etc. wherein are best with ammoniacal liquor, ammonia concn is advisable 7~10%.Because ammoniacal liquor is a kind of weak base, with TiCl
4When effect generates precipitation, can reduce generating sedimentary speed, make the precipitation granularity of generation little and even, be more conducive to next step dispergation, ammoniacal liquor can decompose fully at a certain temperature in addition, can residual other ion and influence TiO after the colloidal sol moulding thus
2The character of material.The acid of being adopted is mineral acid, as HCl, and HNO
3, H
2SO
4Deng, wherein with HCl, HNO
3Be the best.Acidity i.e. [H
+]/[Ti] mol ratio be the preparation in of paramount importance factor, by the allotment [H
+]/[Ti] mol ratio can control the size-grade distribution of colloidal sol, [H
+]/[Ti] scope of mol ratio is generally 0.2~1.0, [H wherein
+]/[Ti]=0.4~0.6 o'clock the preparation colloidal sol median size minimum, it is the narrowest, the most stable to distribute, and can keep some months.The preparation temperature scope is 0~90 ℃, and is wherein suitable with 60~80 ℃.
Give further instruction below by embodiment to preparation method provided by the invention.
Accompanying drawing 1 TiO
2Size-grade distribution (the H of colloidal sol
+/ Al=0.5)
The XRD spectra of accompanying drawing 2 sample after treatment of different temperature (● Detitanium-ore-type TiO
2, the rutile TiO
2, NH
4Cl)
The graph of pore diameter distribution of accompanying drawing 3 sample after 450 ℃ of roastings
Accompanying drawing 4 different pH values are [PtCl down
4]
2-Ion is at TiO
2On adsorption curve
Example 1.TiO
2The preparation of colloidal sol.
Take by weighing 11.4 gram TiCl
4Place separating funnel, after dropwise joining in the HCl solution of 25ml37%, dropwise add the 70ml secondary deionized water again, after stirring half an hour, drip 7%~10% ammoniacal liquor again and o'clock generate white precipitate to pH=6~7, aging one hour, filter, wash (each wash agitation is half an hour approximately) to there not being Cl with 40~50 ℃ of secondary deionized water
-Ion.Then this throw out is joined in the secondary deionized water of 200ml, add the HNO of a certain amount of 1.6M
3Solution, 70 ℃ were stirred dispergation 48 hours down, promptly obtain the TiO of size-grade distribution homogeneous
2Colloidal sol.Drying is 24 hours under 50 ℃, and roasting obtained TiO after 3 hours under the certain temperature
2Powder.
Example 2. acidity are to TiO
2The influence of colloidal sol granularity.
Utilize the above-mentioned colloidal sol of transmission electron microscope observing, can find that their micelle all is spherical.Table 1 has been listed different [H
+]/[Ti] TiO under the mol ratio
2The size-grade distribution of colloidal sol.Data show the stability that can control the particle diameter and the colloidal sol of colloidal sol by the concentration of regulating acid, work as H
+/ Ti mol ratio is the median size minimum of colloidal sol of preparation in 0.5 o'clock, and size-grade distribution is the narrowest, and colloidal sol is also the most stable, can place the several months not precipitate or gelling, and the size-grade distribution of this colloidal sol as shown in Figure 1.Table 1 acid concentration is to TiO
2The influence of colloidal sol particle diameter.
Sample | TiO
2Collosol concentration (M)
| H
+/ Ti (mol ratio)
| Median size (nm) | Collosol stability |
????T1 ????T2 ????T3 ????T4 ????T5 ????T6 ????T7 | 0.3125 0.3125 0.3125 0.3125 0.3125 0.3125 0.3125 | 0.08 0.2 0.4 0.5 0.7 1.0 1.2 | ?- 102 45 14 56 96 - | Can not the stable instability of dispergation |
Example 3. crystalline phase analyses.
With X-ray diffraction (XRD) to studying, to understand the variation of crystalline phase in roasting process through differing temps agglomerating sample.Accompanying drawing 2 is without roasting and the XRD spectra after the differing temps roasting behind the example 1 preparation colloidal sol sample drying.Can find to have weak anatase phase, but have tangible NH therein without heat treated gel sample
4The Cl crystalline phase, this be since in this method in order to regulate the ammoniacal liquor and the raw material TiCl of pH value
4In Cl
-Ion generates NH
4Due to the Cl.NH after 450 ℃ of burnings
4The Cl crystalline phase disappears, and shows as Detitanium-ore-type, is the mixed phase of anatase octahedrite and rutile after 600 ℃ of roastings.
Example 4. differential thermals and thermogravimetric analysis
The TiO of this method preparation will be utilized
2The dried sample of colloidal sol carries out heat analysis.As can be seen, from room temperature to 800 two variations ℃ have taken place from its differential thermal curve: room temperature-220 ℃ still is the evaporation of water the gel network, and 260-450 ℃ then is NH
4The decomposition peak of Cl, NH
4Also not having tangible thermal phenomenon the crystalline phase of Cl has been found that 450 ℃ in XRD analysis after takes place.
Example 5. pore structure parameters
Surface-area, aperture and pore size distribution are the important structural parameter of catalytic material.We study the TiO of this method preparation with low-temperature nitrogen adsorption method
2Colloidal sol is dry after the surface-area of the sample of 450 ℃ of roastings and pore structure.Its surface-area is 74.7m
2/ g, pore volume are 0.11ml/g.Accompanying drawing 3 has shown its pore size distribution respectively.Can find that this sample has single pore distribution, its most probable aperture is about about 4.6nm.By they adsorption isothermal line as can be known, be a mesopore material.
The comparative example alkoxide hydrolysis prepares TiO
2Colloidal sol
Get the mixing solutions of certain density titanium isopropylate and Virahol, be added drop-wise in the secondary deionized water of certain volume under 30 ℃, form white precipitate, add an amount of 1.6M salpeter solution, make H
+/ Ti mol ratio is 0.4,30 ℃ of following dispergation 48 hours, obtains stable sols.After this drying sol roasting, the drying and roasting process is described identical with example 1, carries out XRD, differential thermal, and thermogravimetric, analyses such as cryogenic nitrogen absorption are with the TiO that utilizes method preparation in this patent
2Sample relatively finds to utilize the colloidal sol of present method preparation and character and the colloidal sol of alkoxide hydrolysis preparation and the similar performance of material of powder body material thereof.