Method for regulating and controlling crystal transformation process of nano titanium dioxide

A method for regulating and controlling the process of nanometer titanium dioxide transformationTechnical field

[0001] The present invention relates to the field of nano-material preparation, in particular to a method for regulating the crystal transformation process of nano-titanium dioxide.

Background technique

[0002] Nano titanium dioxide (TiO₂), commonly known as nano titanium dioxide, due to its strong ultraviolet absorption capacity, high photocatalytic activity and unique color performance, it is a versatile functional material. According to the different crystal structure, nano-TiO₂It is divided into two types: anatase and rutile. Different crystal structures lead to big differences in their performance and applications. Anatase Nano-TiO₂It has strong light absorption capacity and high catalytic activity. It is one of the earliest semiconductor materials used in the field of photocatalysis. It can be used in the treatment of environmental pollution such as air, water, and soil, as well as new energy fields such as solar cells and lithium-ion batteries. It has become a global solution Important functional materials for energy and environmental issues. Rutile Nano-TiO₂It has unique color flop, UV shielding, and excellent weather resistance. It is widely used in cosmetics, high-end automotive finishes, plastics and other fields. Therefore, it can precisely control nano-TiO₂The crystalline form and phase composition of the product are the precursors to realize its functional characteristics, and have particularly important economic value.

[0003] At present, rutile and anatase nano TiO have been reported₂There are many preparation methods, mainly including: hydrolysis precipitation method, hydrothermal/solvothermal method, sol-gel method, gas phase method, flame method and so on. However, most preparation methods can only produce nano-TiO with one crystal structure₂And, in order to obtain nano TiO with higher crystallinity₂High temperature calcination is usually required. However, high-temperature calcination not only has a complicated production process and high energy consumption, but also causes nano-TiO₂The growth of crystal grains causes sintering, which affects the performance of its products. Therefore, developed a kind of regulation nano TiO₂The method of crystal transformation process is particularly important, which can improve nano-TiO₂The production efficiency and degree of controllability.

Summary of the invention

[0004] The purpose of the present invention is to solve the use of existing technology to regulate nano TiO₂The problem of complex crystal formation process and high energy consumption is to provide a method for regulating the crystal transformation process of nanometer titania. Through the addition of crystal transformation regulator, the TiO can be controlled.₂The unit cell connection method does not require high-temperature calcination to obtain nano-TiO with specific crystal structure and phase composition₂。

[0005] In order to achieve the above-mentioned objective, the present invention provides a method for regulating the transformation process of nanometer titanium dioxide, the method specifically includes the following steps:

[0006] a. Titanium source hydrolysis reaction, the titanium source is added to the solution, stirred and reacted under certain temperature conditions to obtain a titanium precursor solution;

[0007] b. Transfer the obtained titanium precursor solution into the reactor, and under stirring, add the crystal conversion regulator A, react for a period of time under a certain temperature condition, add the crystal conversion regulator B, and stir for 30min;

[0008] c. Heat the above-mentioned slurry at a certain heating rate and keep it at a certain temperature for a period of time;

[0009] d. Adding a pH regulator to adjust the pH to neutral, filter, wash, dry and pulverize to obtain nano titanium dioxide with a certain crystal structure.

[0010] Wherein, the titanium precursor described in step a of the above method is metatitanic acid, butyl titanate alcohol solution, isopropyl titanate alcohol solution, titanium tetrachloride aqueous solution, titanium sulfate aqueous solution, titanyl sulfate aqueous solution One or more mixtures in.

[0011] Wherein, in the hydrolysis reaction of the titanium source described in step a of the above method, the titanium source is metatitanic acid, titanium tetrachloride, titanium sulfate and

In the case of titanyl sulfate, water can be used as a solution to prepare the titanium precursor solution; when the titanium source is organic titanium such as butyl titanate and isopropyl titanate, anhydrous ethanol is used as a solution to prepare the titanium precursor solution.

[0012] Wherein, the concentration of Ti in the titanium precursor solution described in step a of the above method is 1-5 mol/L.

[0013] Wherein, the crystal conversion regulator A described in step b of the above method is one of sodium hydroxide, potassium hydroxide, sodium bicarbonate, ammonium sulfate, ammonia, urea, disodium edetate or Multiple mixtures.

[0014] Wherein, the amount of the crystal conversion regulator A described in step b of the above method is combined with the titanate (with TiO₂Calculate) the molar ratio is 1-10:1.

[0015] Wherein, the reaction temperature described in step b of the above method is 20-120°C.

[0016] Wherein, the crystal conversion regulator B described in step b of the above method is one or more mixtures of hydrochloric acid, hydrogen peroxide, nitric acid, oxalic acid, sulfuric acid, and glacial acetic acid.

[0017] Wherein, the amount of the crystal conversion regulator B described in step b of the above method is combined with the titanate (with TiO₂Calculate) the molar ratio is 0.1-5:1.

[0018] Wherein, the heating rate described in step c of the above method is 0.2-10° C./min.

[0019] Wherein, the heat preservation reaction temperature described in step c of the above method is 25-120°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] Compared with the existing nano TiO₂Compared with the preparation method, the present invention uses a crystal conversion regulator to control TiO₂In the process of crystal conversion, anatase, rutile and mixed crystal nano TiO can be obtained by changing the addition amount of the crystal conversion regulator A and the regulator B.₂. Compared with other methods that have been reported, this method is simpler and more universal. It only needs one production line to produce many kinds of nano-TiO₂。

[0022] Compared with the existing nano TiO₂Compared with the crystal form control method, the present invention controls the TiO by the crystal conversion regulator.₂The kinetic process of crystal transformation, regulating TiO₂The unit cell connection method can obtain different crystal structures without high-temperature calcination, reducing production energy consumption. Its worth mentioning that in the whole TiO₂In the process of crystal conversion, the crystal conversion regulator can not only adjust the TiO₂The crystal structure of TiO can also be adjusted₂Hydrolysis kinetics, thereby regulating TiO₂Grain size. Therefore, the product obtained by this method has high crystallinity, small particle size, good dispersibility, and good technical and economic performance.

Description of the drawings

[0023] Figure 1 is the nano TiO obtained in Example 1₂XRD spectrum;

[0024] Figure 2 is the nano TiO obtained in Example 2₂XRD spectrum;

[0025] FIG. 3 is the nano TiO obtained in Example 3₂XRD spectrum;

[0026] FIG. 4 is the nano TiO obtained in Example 4₂XRD spectrum;

[0027] FIG. 5 is the nano TiO obtained in Example 5₂XRD spectrum;

[0028] FIG. 6 is the nano TiO obtained in Example 6₂XRD spectrum.

detailed description

[0029] The specific embodiments of the present invention are described in detail to make the objectives, technical solutions, and advantages of the present invention clearer. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] The present invention provides a method of regulating the process of nanocrystalline titanium dioxide, wherein the method includes: first, adding a titanium source to the solution, reacting under stirring and a certain temperature conditions to obtain a titanium precursor solution; Transfer the obtained titanium precursor solution into the reaction kettle, add crystal-transforming regulator A under agitation, and react for a period of time under certain temperature conditions

In the meantime, add crystal conversion regulator B and stir for 30 minutes; then, heat the above slurry at a certain heating rate and keep it at a certain temperature for a period of time; finally, add a pH regulator to adjust the pH to neutral, and filter , Washing, drying and crushing to obtain nanometer titanium dioxide with a certain crystal structure.

[0031] In the present invention, the temperature for preparing the titanium precursor solution is not particularly limited, as long as a uniformly dispersed titanium precursor solution can be obtained, for example, it can be at room temperature or 25°C.

[0032] In the present invention, the pH adjuster added is not particularly limited, and it can be a conventional choice in the art. For example, sodium hydroxide solution, potassium hydroxide solution, ammonia water, etc. can be used. Preferably, use economical, green and environmentally friendly raw materials.

[0033] In the present invention, the filtration and washing of the final product are not particularly limited, and can be conventionally selected in the field. For example, filtration can be implemented in plate and frame filters, membrane washing equipment, and membrane filtration equipment; when washing, desalinated water can be used to wash to the wash water conductivity of W120us/cm.

[0034] In the present invention, there is no particular choice for the implementation of the drying and pulverization, and it can be a conventional choice in the art. For example, the drying can be implemented in equipment such as flash drying, spray drying, oven drying, etc.; pulverization can be It is implemented in grinding equipment and jet mill.

[0035] Hereinafter, the present invention will be described in detail through examples.

Example 1

[0037] 1000mL metatitanic acid solution (with TiO₂(Total, 5mol/L) was added to 430mL deionized water, stirred and reacted at 30°C for 30min to obtain a white precursor slurry. Transfer the white precursor slurry obtained above into the reaction kettle, add 1800mL potassium hydroxide aqueous solution (7.8mol/L), stir and react at 100°C for 90min, then add 480mL hydrochloric acid and 46mL nitric acid solution, stir and react for 30min; turn on the heating Switch, the temperature is increased to 98°C at a heating rate of 8°C/min, and the temperature is kept for 100 minutes. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0038] Figure 1 is the TiO prepared in Example 1₂X-ray diffraction spectrum.

Example 2

[0040] 1144 mL of butyl titanate solution was added to 856 mL of absolute ethanol, and the reaction was stirred at 30° C. for 30 min to obtain a butyl titanate precursor solution. Transfer the butyl titanate precursor solution obtained above into the reactor, add 1200mL sodium hydroxide aqueous solution (2mol/L) and 100g urea, stir and react at room temperature for 80min, then add 20g oxalic acid, 800mL hydrochloric acid and 20mL sulfuric acid solution, Stir the reaction for 30 minutes; turn on the heating switch, increase the temperature to 105 °C at a heating rate of 5 °C/min, and keep the temperature for 120 minutes. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0041] Figure 2 is the TiO prepared in Example 2₂X-ray diffraction spectrum.

Example 3

[0043] 550 mL of titanium tetrachloride solution was added to 1450 mL of deionized water, and the reaction was stirred at room temperature for 30 min to obtain a titanium tetrachloride precursor solution. Transfer the titanium tetrachloride precursor solution obtained above into the reaction kettle, add 5000mL sodium hydroxide aqueous solution (5mol/L) and 3000mL sodium bicarbonate aqueous solution (0.5mol/L) successively, stir and react at room temperature for 60min, then, Add 600mL hydrochloric acid, 46mL sulfuric acid and 10mL hydrogen peroxide solution, stir the reaction for 30min; turn on the heating switch, increase the temperature to 95°C at a heating rate of 5°C/min, and keep the reaction temperature for 90min. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0044] Figure 3 is a 70 prepared in Example 3₂* Ray diffraction spectrum.

Example 4

[0046] 550 mL of titanium tetrachloride solution was added to 1450 mL of deionized water, and the reaction was stirred at room temperature for 30 min to obtain a titanium tetrachloride precursor solution. Transfer the titanium tetrachloride precursor solution obtained above into the reaction kettle, add 7000mL potassium hydroxide aqueous solution (3mol/L) and 600mL ammonia aqueous solution (mass fraction 25%) successively, stir and react at room temperature for 100min, then add in sequence 700mL hydrochloric acid, 65mL glacial acetic acid and 45mL nitric acid solution, stirred and reacted for 30min; turned on the heating switch, heated to 105°C at a heating rate of 4°C/min, and kept the reaction for 100min. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0047] Figure 4 is the 70 prepared in Example 4₂The X-ray diffraction spectrum.

Example 5

[0049] 550 mL of titanium tetrachloride solution was added to 1150 mL of deionized water, and the reaction was stirred at room temperature for 60 min to obtain a titanium tetrachloride precursor solution. The titanium tetrachloride precursor solution obtained above was transferred to the reaction kettle, and 6000mL sodium hydroxide aqueous solution (3mol/L), 68g ammonium sulfate and 600mL ammonia solution (mass fraction 25%) were sequentially added, and the reaction was stirred at room temperature for 100min. Then, 600mL hydrochloric acid, 48mL sulfuric acid and 45mL hydrogen peroxide solution were added in sequence, and the reaction was stirred for 30min; the heating switch was turned on, the temperature was raised to 100°C at a heating rate of 5°C/min, and the reaction was kept for 90min. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0050] Figure 5 is a 70 prepared in Example 5₂The X-ray diffraction spectrum.

Example 6

[0052] 1200 g of titanium sulfate solution was added to 1666 mL of deionized water, and the reaction was stirred at room temperature for 30 minutes to obtain a titanium sulfate precursor solution. Transfer the precursor solution obtained above into the reaction kettle, add 5000mL sodium hydroxide aqueous solution (3mol/L) and 600mL ammonia aqueous solution (mass fraction 25%) successively, stir and react at room temperature for 100min, then, successively add 700mL hydrochloric acid and 65mL A solution of glacial acetic acid and 45mL nitric acid was stirred and reacted for 30 minutes; the heating switch was turned on, the temperature was raised to 105°C at a heating rate of 4°C/min, and the reaction was kept warm for 120 minutes. After the reaction is over, add an appropriate amount of sodium hydroxide solution, adjust the pH of the slurry to between 6.5-8, and naturally cool to room temperature, then filter, add deionized water to wash, and finally dry and crush to obtain nano-TiO₂。

[0053] Figure 6 is a 70 prepared in Example 6₂The X-ray diffraction spectrum.

[0054] The crystal form and ratio of the nanometer titanium dioxide sample were determined by XRD diffraction.

[0055] The test results are shown in Table 1:

[0056] Table 1

<td rowspan="4">[0057]</td><td></td><td>Example 1</td><td>Example 2</td><td>Example 3</td><td>Example 4</td><td>Example 5</td><td>Example 6</td>

<td>Rutile type ratio (%)</td><td>100</td><td>0</td><td>0</td><td>100</td><td>46.7</td><td>0</td>

<td>Anatase ratio (%)</td><td>0</td><td>100</td><td>100</td><td>9</td><td>53.3</td><td>100</td>

<td>Grain size (nm)</td><td>68.4</td><td>5.9</td><td>6.1</td><td>9.7</td><td>5.9</td><td>5.6</td>