Method for preparing composite titanium oxide nanoparticles

The first method for preparing composite titanium dioxide nanoparticles Technical Field The present invention relates to a method for preparing titanium dioxide nanoparticles, specifically, a new type of rutile/anatase type composite titanium dioxide nanoparticles and metal-doped rutile/rutile/ Preparation method of anatase type composite titanium dioxide nano particles.

BACKGROUND OF THE INVENTION The existing method for synthesizing titanium dioxide nanoparticles, that is, the preparation method of ICHINOSE in Japan, is to dissolve titanium metal or titanium compound in hydrogen peroxide to form a titanium metal peroxide complex polymer, and then add alkali to precipitate the titanium hydroxide. Finally, the precipitate is heated and dried at 100°C to generate peroxide-modified anatase-type titanium dioxide nanoparticles.

The preparation method of ICHINOSE in Japan is to first change the titanium precursor into titanium hydroxide, then add hydrogen peroxide to form a titanium peroxide metal complex polymer, and then further boil and dry to obtain anatase titanium dioxide nano particle. The existing preparation methods of titanium dioxide nanoparticles have no discussion of particle size and morphology control, whether from published patents or paper reports. It can be inferred that it is difficult to control the particle size and morphology.

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for preparing composite titanium dioxide nanoparticles, and the particle size and morphology of the obtained nanoparticles can be adjusted. The titanium dioxide nano particles prepared by the invention can be used not only as photocatalytic materials but also as supports for supported catalysts.

In order to achieve the above objective, the technical solution adopted by the present invention is as follows: The present invention is to dissolve the titanium precursor in a special organic solvent, add hydrogen peroxide, then boil in a water bath for more than 4 hours, and heat and dry to obtain rutile/anatase type Composite titanium dioxide nanoparticles.

A method for preparing composite titanium dioxide nanoparticles,

1) Dissolve the special titanium metal complex precursor in a special organic solvent to form a solution;

The titanium metal complex is a titanium-containing compound that is soluble in an organic solvent, such as titanium isopropoxide, titanium 2-methylpropoxide, titanium tetraisopropoxide, or titanium tetramethoxide; and the organic solvent is diethylene glycol Alcohol reagents such as monoethyl alcohol, ethylene glycol monoacetyl, diethylene glycol monobutyl, terephthalic acid, isophthalic acid or ethylene glycol phenyl alcohol; titanium metal complex is soluble in organic The weight and volume concentration in the solvent is 0.15-3g/ml; the boiling time in the water bath is N4 hours; the heating and drying temperature is 100-120°C, and the time is 12-24 hours.

2) Add hydrogen peroxide to the above solution, then boil the reaction in a water bath, heat and dry after the reaction to obtain rutile/anatase composite titanium dioxide nanoparticles.

After boiling in a water bath, a precious metal uranium catalyst is added to catalytically decompose and remove excess hydrogen peroxide, and then heat and dry to obtain rutile/anatase composite titanium dioxide nanoparticles; the hydrogen peroxide

The concentration of 200810012663.X is 5-90% (volume ratio), and the volume-to-volume ratio of the solution obtained in step 1) is 3-30o. The step 1) solution can also be added with elements M, Μ is V, Fe , Ni, Mo, W, Nb, Ta, Sn, Sb or Bi, the doping amount is M/Ti molar ratio of 0.001-0.1; element M is added in the form of a compound that can be dissolved in an organic solvent Step 1) In solution, such as soluble salts containing element M, such as: M complex of acetylacetone and its derivatives, ethylenediaminetetraacetic acid and its related M complexes, etc.

After heating and drying to obtain the rutile/anatase composite titanium dioxide nanoparticles, they can be further heat treated, the heat treatment temperature is >150°C and the time is N1 hour.

Compared with the existing preparation method, the present invention has the following characteristics: The present invention can also synthesize rutile/anatase type composite titanium dioxide nanoparticles and metal doped rutile/anatase type composite titanium dioxide nanoparticles by using titanium metal powder. .

The present invention can also synthesize new rutile/anatase type composite titanium dioxide nanoparticles and metal doped rutile/anatase type composite titanium dioxide nanoparticles by using a titanium precursor containing at least one element of oxygen and hydrogen.

The common point of the present invention and the Japanese ICHINOSE preparation method is that by adding hydrogen peroxide, the titanium precursor is transformed into a titanium peroxide metal complex polymer. Then the polymer of this titanium peroxide metal complex is boiled and dried at about 100°C to obtain titanium dioxide nanoparticles.

The difference between the present invention and the prior art is:

1) In the present invention, the titanium precursor is dissolved in an organic solvent, and hydrogen peroxide is added to boil to directly obtain a titanium metal peroxide complex polymer. Afterwards, a noble metal clamp catalyst is added to catalytically decompose and remove excess hydrogen peroxide, and then boil and dry to obtain rutile/anatase type composite titanium dioxide nanoparticles. In other words, the present invention directly obtains the composite phase of rutile/anatase type titanium dioxide nanoparticles, rather than pure anatase type titanium dioxide nanoparticles; and the existing preparation method can only obtain anatase type titanium dioxide nanoparticles. particle.

Furthermore, the present invention can also prepare metal-doped rutile/anatase composite titanium dioxide nanoparticles by adding precursors of other metals. In photocatalysis research, through metal doping, such as the known doping of iron, iron, bismuth, etc., titanium dioxide nanoparticles can be responsive to visible light, thereby improving their photocatalytic efficiency and achieving effective solar energy. use.

2) At the same time, the present invention can control the particle size and morphology of composite titanium dioxide nanoparticles by adjusting the volume of the organic solvent and the amount of metal doping, which meets the requirements of nano-level control of particles that are difficult to achieve by general preparation methods.

The particle size and morphology of the rutile/anatase composite titanium dioxide nanoparticles can be controlled by adjusting the volume and dosage of the titanium precursor and the organic solvent. That is, compared with existing preparation methods, the chemical solution preparation method of the present invention can control the particle size and morphology of titanium dioxide nanoparticles.

When controlling the particle size and morphology of metal-doped rutile/anatase composite titanium dioxide nanoparticles, it can be achieved by adjusting the volume and dosage of the titanium precursor and organic solvent, or by adjusting the amount of metal doping.

3) The rutile/anatase type composite titanium dioxide nano particles and metal doping obtained in the present invention

200810012663.X The rutile/anatase type composite titanium dioxide nanoparticles have uniform particle size and high crystallinity, that is to say, they have a special morphology.

4) The metal doping amount of the metal-doped titanium dioxide nanoparticles prepared by the present invention is significantly greater than that of the metal-doped titanium dioxide nanoparticles prepared by methods such as sol-gel and co-precipitation reported in the literature. For example, in the case of iron doping, the maximum doping amount reported in the literature so far is about 6.5% (mol %), and this preparation method can make the doping amount of iron at least 10% ( Mole percentage).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a powder X-ray diffraction pattern of a new type of rutile/anatase type composite titanium dioxide and its iron-doped rutile/anatase type composite titanium dioxide nanoparticles. Before iron doping, the new titanium dioxide nanoparticles prepared by the chemical solution method have the coexistence of rutile/anatase crystal phases. Through iron doping, the rutile crystal phase changes less and the anatase crystal phase increases.

Figure 2 shows the UV-vis diffuse reflectance spectra of new rutile/anatase composite titanium dioxide and iron-doped rutile/anatase composite titanium dioxide nanoparticles. It can be clearly seen that there is significant absorption in the visible light absorption area after iron doping. From the powder X-ray diffraction pattern and UV-vis diffuse reflectance spectrum, it can be seen that the doping of iron has two effects: one is to increase the anatase crystal phase; the other is to make the titanium dioxide nanoparticles have obvious absorption of visible light.

Figure 3 is a powder X-ray diffraction pattern of new rutile/anatase composite titanium dioxide nanoparticles and iron-doped rutile/anatase composite titanium dioxide nanoparticles after heat treatment at 500°C for 2 hours. It can be seen that through heat treatment, most of the rutile/anatase composite titanium dioxide nanoparticles are converted into rutile crystal phases, while the crystallinity of the iron-doped rutile/anatase composite titanium dioxide nanoparticles increases, and the ratio of the rutile crystal phases Significantly increased.

Figure 4 is a typical 5? Fe Mossbauer spectrum of the new iron-doped rutile/anatase composite titanium dioxide nanoparticles at room temperature. The results of Mössbauer spectroscopy show that when the doping amount of iron is x-1% (mole percentage, the same below), iron only exists in the rutile phase with small structural distortion; when x-2% and 5%, iron exists in the structure The rutile phase with small distortion also exists in the anatase phase with relatively large structural distortion; when x = 10%, iron basically enters the anatase phase with relatively large structural distortion.

Figure 5 is a typical transmission electron micrograph of a new type of rutile/anatase type composite titanium dioxide and iron-doped rutile/anatase type composite titanium dioxide nanoparticles. It can be seen that the nanoparticles all have good crystallinity, and the morphology is ellipsoidal. For each sample, the particle size is basically the same. When there is no iron doping, the particle size is larger, about 40 nanometers, while when there is iron doping, the particle size becomes significantly smaller. When the doping amount x = 1%, the particle size is about 8 nanometers, and then as the doping amount increases, the particle size tends to increase, but when x = 5%, the particle size is less than 40 nanometers. That is, the doping of iron can inhibit the growth of titanium dioxide nanoparticles, that is to say, the particle size and morphology of titanium dioxide nanoparticles can be controlled by adjusting the doping amount of iron.

Specific embodiment one, new rutile/anatase type composite titanium dioxide nanoparticles Example 1

200810012663.X Preparation of rutile/anatase composite titanium dioxide nanoparticles: 2.7 g of titanium isopropoxide was added to a 500 ml beaker, and then 10 ml of ethylene glycol monoacetate organic solvent was added. After that, add 30 ml of 45% hydrogen peroxide while stirring. While continuing to stir, put the mixed solution in a water bath and boil for 4 hours. In order to prevent the solution from evaporating when boiling, the beaker should be covered with an evaporation dish. After that, several pieces of metal clamp catalyst are added to the mixed solution to decompose and remove excess hydrogen peroxide. Then, the solution is slowly evaporated to dryness, and the obtained residue is dried at 120°C for 24 hours to obtain new rutile/anatase composite titanium dioxide nanoparticles with uniform particle size and high crystallinity.

Powder X-ray diffraction was used to analyze the crystal phase, purity and crystal phase change of the obtained nanoparticles before and after heat treatment. The light absorption properties of the obtained nanoparticles were analyzed by ultraviolet-visible diffuse reflection. The particle size and monodispersity were observed. The results are shown in Figures 1, 2, 3, and 5.

Example 2 Preparation of novel rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies: 2.7 grams of titanium 2-methylpropoxide, titanium tetraisopropoxide, and titanium tetramethoxide were added to 500 ml of titanium dioxide. In a different beaker, add 10 ml of ethylene glycol monoethyl ether organic solvent. After that, the operation steps are the same as in Example 1, and three new rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies can be obtained. As in Example 1, the obtained nanoparticles were characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection and transmission electron microscopy. The results show that different titanium precursors can significantly affect the size of titanium dioxide nanoparticles and the molar ratio of rutile/anatase phase. The results are shown in Figures 1, 2, 3, and 5.

Example 3 Preparation of new rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies: Four parts of 2.7 g titanium isopropoxide were added to a 500 ml beaker, and then 5, 20,

30, 40 ml of ethylene glycol monoacetaldehyde organic solvent. After that, the operation steps are the same as in Example 1, and new rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies can be obtained. As in Example 1, the obtained nanoparticles were characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection and transmission electron microscopy. The results show that the volume of ethylene glycol monoacetate organic solvent can significantly affect the particle size, dispersion of titanium dioxide nanoparticles and the molar ratio of rutile/anatase phase. The results are shown in Figures 1, 2, 3, and 5.

Example 4 Preparation of novel rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies: Five portions of 2.7g titanium isopropoxide were added to a 500ml beaker, and then 10ml of diethylene glycol mono Organic solvents for acetylene, diethylene glycol monobutyrate, terephthalate, isophthalic acid, and ethylene glycol benzoate. After that, the operation steps are the same as in Example 1, and new rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies can be obtained. As in Example 1, the obtained nanoparticles were characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection and transmission electron microscopy. The results show that the type of organic solvent can also significantly affect the particle size of titanium dioxide nanoparticles and the molar ratio of rutile/anatase phase. The results are shown in Figures 1, 2, 3, 4, and 5.

200810012663.X Second, a new type of metal-doped rutile/anatase type composite titanium dioxide nanoparticles Example 1 Iron-doped rutile/anatase type composite titanium dioxide nanoparticles: 4 parts of 1.7 g of titanium isopropoxide were added to 500 ml respectively In the beaker, add 10 ml of ethylene glycol monoacetate organic solvent, the mixed solution is named as solution 1-1, 1-2, 1-3, 1-4 ο Weigh 0.02, 0.05, 0.11, 0.23g respectively Add the iron acetylacetone complex (ie acetylacetone complexed iron) into a 50 ml glass bottle with a lid, and then add 10 ml of ethylene glycol monoethyl ether organic solvent, shake well until the iron acetylacetone complex is completely dissolved. Name this mixed solution solution II-1, 11-2, II-3, After II-4o, while continuously stirring Solution I, slowly add Solution II to Solution I. While continuing to stir, add 30 ml of 45% hydrogen peroxide to the mixed solution, and boil the mixed solution in a water bath for 4 hours. When 45% hydrogen peroxide was just added, the reaction was very violent. In order to prevent the solution from splashing, a certain amount of pure water can be added to the mixed solution. When boiling in a water bath, in order to prevent evaporation of the solution, an evaporating dish can be covered on the beaker. After 4 hours of heating and boiling, 3 small pieces of metal clamp catalyst are added to the mixed solution to catalytically decompose and remove excess hydrogen peroxide. Then, the solution was slowly evaporated to dryness, and the obtained residue was dried at 120°C for 24 hours to obtain new iron-doped rutile/anatase composite titanium dioxide nanoparticles with uniform particle size and high crystallinity. Powder X-ray diffraction was used to analyze the crystal phase, purity and crystal phase change of the obtained nanoparticles before and after heat treatment. The light absorption properties of the obtained nanoparticles were analyzed by ultraviolet-visible diffuse reflection.⁵⁷Fe Mössbauer spectroscopy analyzed the presence of iron in the obtained nanoparticles, and observed the particle size and monodispersity of the obtained nanoparticles with a transmission electron microscope. The results clearly show that the amount of iron doping can affect the size of titanium dioxide nanoparticles, the molar ratio of rutile/anatase phase and the light absorption properties. After iron doping, titanium dioxide nanoparticles have obvious absorption in the visible light range.

Heating at 500°C for 2 hours can improve the crystallinity of the new iron-doped rutile/anatase composite titanium dioxide nanoparticles, and at the same time adjust the molar ratio of rutile/anatase crystal phase. The obtained nanoparticles were also characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection, Fe Mössbauer spectroscopy and transmission electron microscopy. The results are shown in Figures 1, 2, 3, 4, and 5.

Example 2 Hook-doped rutile/anatase type composite titanium dioxide nanoparticles: Change the iron acetylacetone complex in Example 1 to a brick acetylacetone complex (ie, acetylacetone complex) to synthesize particles Novel hook-doped rutile/anatase composite titanium dioxide nanoparticles with uniform diameter and high crystallinity. Powder X-ray diffraction was used to analyze the crystal phase, purity, and crystal phase change of the obtained nanoparticles. The ultraviolet-visible diffuse reflection was used to analyze the light absorption properties of the obtained nanoparticles. The particle size of the obtained nanoparticles was analyzed by transmission electron microscope. The diameter and monodispersity were observed.

Heating at 500°C for 2 hours can make the crystallinity of the obtained new-type rutile/anatase composite titanium dioxide nanoparticles become better, and at the same time, the molar ratio of rutile/anatase crystal phase can be adjusted.

200810012663.X also used powder X-ray diffraction, ultraviolet-visible diffuse reflection and transmission electron microscopy to characterize the obtained nanoparticles.

Example 3 Preparation of iron-doped rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies: the titanium isopropoxide in Example 1 can be changed to titanium 2-methylpropoxide or tetraisopropoxide Titanium alkoxide or titanium tetramethoxide, the organic solvent ethylene glycol monoacetaldehyde can be changed to diethylene glycol monoacetaldehyde or diethylene glycol monobutyraldehyde or terephthalate or metaxylylene or glycol benzene In consideration, the volume of organic solvent can be changed from 10 ml to 5 or 20 or 30 or 40 ml. Other conditions remain unchanged. Changing one of the above three conditions can synthesize iron-doped rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies. The obtained nanoparticles were also characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection,'? Fe Mössbauer spectroscopy and transmission electron microscopy. The results are shown in Figure 1, 2, 3, 4, 5 shown. "Example 4 Preparation of brick-doped rutile/anatase composite titanium dioxide nanoparticles with different particle sizes and morphologies: the titanium isopropoxide in Example 2 can be changed to titanium 2-methylpropoxide or tetraisopropylate Titanium propoxide or titanium tetramethoxide, the organic solvent ethylene glycol monoacetate can be changed to diethylene glycol monoacetate or diethylene glycol monobutyryl or terephthalic acid or isophthalic acid or ethylene glycol For benzene, the volume of the organic solvent can be changed from 10 ml to 5 or 20 or 30 or 40 ml. Other conditions remain unchanged, and one of the above three conditions can be changed to synthesize different particle size and morphology doped rutile/sharp Titanite-type composite titanium dioxide nanoparticles. The obtained nanoparticles were also characterized by powder X-ray diffraction, ultraviolet-visible diffuse reflection and transmission electron microscopy.

200810012663.X