An electronic-grade spherical titanium dioxide and its preparation method

Abstract

The present invention discloses an electronic-grade spherical titanium dioxide and a preparation method thereof. The preparation method is as follows: industrial metatitanic acid powder is added to a sulfuric acid solution, and then a surfactant and a complexing agent are added. After reaction, an acidolysis solution is obtained, which is filtered and diluted to obtain a titanyl sulfate solution; a dispersant is added for hydrolysis reaction, and after heat preservation and aging, a titanium dioxide slurry is obtained; after filtration and washing, the pH is adjusted, and after stirring and aging, ammonium sulfate is added, and reaction gives a powder; the powder is calcined, cooled and ground to obtain the product. The present invention uses industrial metatitanic acid powder as a raw material, and through technological processes such as acidolysis, hydrolysis, precipitation and calcination, realizes the preparation of high-quality titanium dioxide products. By adding a self-made complexing agent, metal impurities in metatitanic acid are successfully removed, and the self-made dispersant introduced in the hydrolysis stage effectively reduces the agglomeration phenomenon, and finally a titanium dioxide product with excellent dispersibility, high purity and good sphericity is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide, and particularly relates to an electronic-grade spherical titanium dioxide and a preparation method thereof. Background Art

[0002] Due to its unique physical and chemical properties and excellent optical properties, titanium dioxide has become an indispensable multi-functional material in modern industry. It has characteristics such as a high refractive index, strong chemical stability, and non-toxicity, and is widely used in traditional fields such as coatings, plastics, papermaking, rubber, and food additives. At the same time, because of its high dielectric constant and resistivity and semiconductor characteristics, it also plays an important role in high-tech industries such as electronic ceramics, semiconductor capacitors, thermistors, and special glass.

[0003] Titanium dioxide is usually manufactured in the anatase or rutile crystal form. Among them, the rutile form is more favored in industrial applications because of its higher refractive index and better weather resistance. In recent years, with the development of high-end manufacturing industries such as liquid crystal materials, precision sensors, and aerospace, the market demand for high-purity titanium dioxide has been continuously increasing, and the quality requirements for it have become increasingly strict, especially the control of impurity content such as iron.

[0004] The preparation methods of titanium dioxide are mainly divided into gas-phase methods and liquid-phase methods. Gas-phase methods include TiCl4 gas-phase hydrogen flame hydrolysis method, TiCl4 gas-phase oxidation method, titanium alkoxide gas-phase hydrolysis method, etc. These methods can produce high-quality nano-scale titanium dioxide, but due to high equipment requirements, complex operations, high costs, etc., their application scope is relatively small. Liquid-phase methods include sulfuric acid method, hydrochloric acid method, sol-gel method, chloride liquid-phase hydrolysis method, hydrothermal method, microemulsion method, etc. Compared with gas-phase methods, liquid-phase methods have lower equipment requirements, simpler operations, wider raw material sources, and lower costs, so they have become more common preparation methods.

[0005] At present, the industrial production of titanium dioxide mainly uses the gas-phase TiCl4 method, the liquid-phase sulfuric acid method, and the titanium alkoxide liquid-phase hydrolysis method. In China, the sulfuric acid method is the main production method. The sulfuric acid method has the advantages of simple and mature process, easy availability of raw materials, low cost, and simple equipment, but it is easy to introduce impurities and affect the product purity.

[0006] In the process of producing titanium dioxide by the sulfuric acid method, metatitanic acid is an important intermediate product. It is obtained by hydrolyzing titanyl sulfate after reacting ilmenite with sulfuric acid and going through steps such as purification, freezing to remove ferrous sulfate, pressure filtration, and concentration. Metatitanic acid is not only an important raw material for preparing titanium dioxide, but also can be used to prepare titanium-containing products such as nano-scale titanium dioxide, titanium sulfate, and titanyl sulfate.

[0007] However, due to differences in raw materials and production processes, unpurified metatitanic acid usually contains a large amount of metal impurities such as iron, magnesium, cobalt, manganese, chromium, niobium, sodium, or potassium. These impurities not only affect the hue of the final product but also cause lattice deformation, severely reducing the product performance. For example, when preparing titanium dioxide, these impurities will cause the product hue to be yellowish or reddish, reducing the whiteness; when preparing nanoscale titanium dioxide, the impurities will become crystallization centers, resulting in uneven particle size distribution and affecting its catalytic application effect.

[0008] Therefore, the purification of metatitanic acid, especially the removal of metal impurity ions therein, has become a key step in improving the quality of titanium dioxide.

[0009] Chinese patent document CN1613775A discloses a method for preparing rutile-type titanium dioxide electronic powder using metatitanic acid as the main raw material: (1) adding hydrochloric acid to metatitanic acid, adjusting the acidity to make pH ≤ 2.0, and adding powdered reducing agents such as aluminum powder, zinc powder, or iron powder for reaction. The weight of the added reducing agent is 0.5 - 2% of the net weight of TiO2 in metatitanic acid; (2) adjusting the pH value of the material obtained after step (1) treatment to make its pH value in the range of 2.0 - 4.0, and washing the above material with pure water; (3) adding 0.5 - 1.5% of a mixture composed of arsenic sulfide (realgar As4S4 or orpiment As2S3) and arsenic trioxide As2O3 to the material prepared in step (2) and stirring and mixing; (4) calcining the material prepared in step (3) in the temperature range of 820 - 960 °C and holding for 2.5 - 5 hours, and then allowing it to cool naturally to room temperature to obtain the finished product.

[0010] Current purification methods mainly include water washing, bleaching, salt treatment, etc., but these methods have problems such as cumbersome operations and possible introduction of new impurities. To meet the strict requirements for the purity of titanium dioxide in high-end application fields, developing more effective purification methods for metatitanic acid has become the focus of current research. Summary of the Invention

[0011] To solve the deficiencies of the existing technology, the purpose of the present invention is to provide an electronic-grade spherical titanium dioxide and its preparation method. Using industrial metatitanic acid powder as the raw material, through technological processes such as acidolysis, hydrolysis, precipitation, and calcination, the preparation of high-quality titanium dioxide products is achieved. By adding a self-made complexing agent, metal impurities in metatitanic acid are successfully removed, significantly improving the purity of the final titanium dioxide product. The self-made dispersant introduced in the hydrolysis stage effectively reduces the agglomeration phenomenon, laying a foundation for the subsequent preparation of titanium dioxide with excellent dispersibility and high sphericity.

[0012] To achieve the above purpose, the present invention adopts the following technical solutions:

[0013] A method for preparing electronic-grade spherical titanium dioxide, comprising the following steps:

[0014] (1) Add industrial metatitanic acid powder to sulfuric acid solution, then add surfactant and complexing agent, heat and react to obtain acidolysis solution, filter and dilute the acidolysis solution to obtain titanyl sulfate solution;

[0015] (2) Add dispersant to titanyl sulfate solution, carry out hydrolysis reaction, and obtain titanium dioxide slurry after heat preservation and aging;

[0016] (3) Filter and wash the titanium dioxide slurry, adjust the pH, stir and age, then add ammonium sulfate, filter and dry the product to obtain powder;

[0017] (4) Calcinate, cool and grind the powder obtained in step (3) to obtain the electronic grade spherical titanium dioxide.

[0018] Preferably, in step (1), the concentration of sulfuric acid solution is 85-98 wt%; the dosage ratio of industrial metatitanic acid powder to sulfuric acid solution is 1 g: 2-10 mL; the dosages of surfactant and complexing agent are respectively 0.5-2 wt% and 0.01-0.5 wt% of industrial metatitanic acid powder.

[0019] Preferably, in step (1), the surfactant is one or more of anionic surfactant and nonionic surfactant; the heating reaction condition is to react at 90-150 °C for 1-6 h; after the reaction, dilute the acidolysis solution with deionized water to obtain a titanyl sulfate solution with a concentration of 200-500 g / L.

[0020] Preferably, in step (1), the structural formula of the complexing agent is one of formula I or formula II:

[0021]

[0022] More preferably, in step (1), the structural formula of the complexing agent is as follows:

[0023]

[0024] Specifically, in step (1), the preparation method of the complexing agent includes the following steps:

[0025] Add iminodiacetic acid and potassium carbonate to tetrahydrofuran, slowly drop in trimellitic acid chloride under ice bath condition, stir and react under ice bath condition, rotary evaporate the product to remove the solvent tetrahydrofuran, then add ethyl acetate for extraction and separation, rotary evaporate, and recrystallize the product in ethyl acetate to obtain the complexing agent.

[0026] Preferably, the molar ratio of iminodiacetic acid, potassium carbonate and trimellitic acid chloride is 1: 2.5-4: 2-3.1.

[0027] Preferably, trimellitic acid chloride is added dropwise over 30 - 90 minutes, and the stirring reaction conditions are stirring reaction at 0 - 5°C for 1 - 6 hours.

[0028] Under ice bath conditions (0 - 5°C), iminodiacetic acid and potassium carbonate are mixed in a tetrahydrofuran solvent, then trimellitic acid chloride is slowly added dropwise, and the reaction continues to stir in the ice bath. After the reaction is completed, the tetrahydrofuran solvent is removed by a rotary evaporator, then the product is extracted and separated with ethyl acetate, and then the ethyl acetate is removed again using a rotary evaporator. Finally, recrystallization from ethyl acetate gives the final product complexing agent.

[0029] The core of this reaction is the acylation reaction between acyl chloride and amino group to form N - substituted amide. Trimellitic acid chloride contains three acyl chloride groups and can undergo acylation reaction with the secondary amino group in iminodiacetic acid. The acylation reaction in this step is carried out in a low - temperature ice bath environment to slow down the reaction rate, thereby increasing the product yield and reducing the occurrence of side reactions. Slowly adding dropwise trimellitic acid chloride can ensure that the reaction proceeds more thoroughly and avoid an increase in side reactions caused by local excess.

[0030] As a basic substance, potassium carbonate not only removes acidic impurities in the raw materials but also provides the basic environment required for the reaction, promoting the progress of the reaction. Potassium carbonate neutralizes by - products such as hydrochloric acid generated during the reaction process to ensure that the reaction medium remains basic.

[0031] In the post - treatment step after the reaction is completed, the tetrahydrofuran solvent is removed by a rotary evaporator (rotary evaporation) to obtain a preliminary product. Subsequently, the reaction mixture is extracted with ethyl acetate to separate non - polar impurities, and then the ethyl acetate is removed by rotary evaporation to obtain the refined product required for recrystallization. Finally, recrystallization in ethyl acetate further purifies the product to ensure that the final generated complexing agent has a high purity.

[0032] Preferably, in step (2), the dosage ratio of the dispersant to the titanyl sulfate solution is 0.1 - 3 g: 100 mL.

[0033] Preferably, in step (2), the hydrolysis reaction conditions are hydrothermal reaction at 90 - 130°C and 0.2 - 1 MPa for 2 - 12 hours, and heat preservation and aging for 1 - 3 hours.

[0034] Preferably, in step (2), the structural formula of the dispersant is as follows:

[0035]

[0036] Specifically, in step (2), the preparation method of the dispersant includes the following steps:

[0037] a. Dissolve poly(succinimide) in DMSO to obtain a PSI solution; dissolve dopamine hydrochloride in DMSO, then add triethylamine and ultrasonically oscillate to obtain a dopamine solution; add the dopamine solution to the PSI solution and reflux react under a nitrogen atmosphere to obtain a PSI-DA intermediate reaction solution.

[0038] b. Dissolve glutamic acid in DMSO, then add triethylamine and ultrasonically oscillate to obtain a glutamic acid solution; add the glutamic acid solution to the intermediate reaction solution, stir and react under a nitrogen atmosphere, adjust the pH with an aqueous sodium hydroxide solution, precipitate the product with acetone, filter, wash with acetone, and dry to obtain the dispersant.

[0039] Preferably, in step a, the dosage ratio of PSI, dopamine hydrochloride, and triethylamine is 40 mmol: 10 - 15 mmol: 8 - 16 mL; the ultrasonic oscillation time is 10 - 30 min; the reflux reaction conditions are reflux reaction at 50 - 70 °C for 18 - 30 h.

[0040] Preferably, in step b, the dosage ratio of glutamic acid and triethylamine is 30 mmol: 10 - 20 mL; the stirring reaction conditions are stirring reaction at 50 - 70 °C for 12 - 20 h, and after the reaction, adjust the pH to 7 - 8.

[0041] Preferably, the molar ratio of poly(succinimide), dopamine hydrochloride, and glutamic acid is 40: 10 - 15: 30 - 25.

[0042] This reaction includes two main steps. First, poly(succinimide) (PSI) reacts with dopamine (DA), and then the PSI-DA intermediate reacts with glutamic acid. In the first step, triethylamine acts as a strong base to neutralize dopamine hydrochloride, releasing free dopamine. The primary amine group (-NH2) of dopamine then undergoes nucleophilic addition to the imide ring of PSI. This process involves the nitrogen atom of the amino group attacking the carbonyl carbon of the imide ring to form a tetrahedral intermediate, and then the intermediate collapses, resulting in the opening of the imide ring and finally grafting dopamine onto the poly(succinimide) molecular chain.

[0043] In the second step reaction, the α-amino group of glutamic acid undergoes a similar nucleophilic addition reaction to the remaining PSI imide ring. This process is similar to the first step and also includes the amino group attacking the carbonyl carbon of the imide ring to form a tetrahedral intermediate, the intermediate collapsing, and the imide ring opening, grafting glutamic acid onto the poly(succinimide) molecule.

[0044] The result of the whole reaction is that some imide rings on the PSI main chain are ring-opened by dopamine, introducing dopamine side chains, and the remaining imide rings are ring-opened by glutamic acid, introducing glutamic acid side chains. The final product is a polymer containing dopamine and glutamic acid side chains, and some unreacted imide rings may remain on the main chain.

[0045] By introducing side chains with specific functions on the PSI skeleton, an amphiphilic polymer with good dispersion performance is successfully synthesized, which combines various action mechanisms such as electrostatic stabilization, steric stabilization, and chemical adsorption, and exhibits an efficient and stable dispersion effect.

[0046] Preferably, in step (3), the pH of the system is adjusted to 8 - 10 with ammonia water, stirred and aged for 2 - 5 h, and the mass ratio of the titanium dioxide slurry to ammonium sulfate is 100:0.5 - 2.

[0047] Preferably, in step (4), it is calcined at 500 - 1000 °C for 2 - 5 h.

[0048] The present invention also claims to protect an electronic-grade spherical titanium dioxide prepared by using the above preparation method.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1) The present invention provides a preparation method of electronic-grade spherical titanium dioxide, which uses easily obtainable industrial metatitanic acid powder as a raw material, and prepares electronic-grade spherical titanium dioxide through processes such as acidolysis, hydrolysis, precipitation, and calcination. D 50 is 50 - 100 nm, TiO2 ≥ 99.9 wt%, Si ≤ 0.05 wt%, Al ≤ 0.005 wt%, Ca ≤ 0.005 wt%, Nb ≤ 0.005 wt%, V ≤ 0.005 wt%, Fe ≤ 0.0005 wt%, Cl ≤ 0.005 wt%, BET = 15 - 30 m 2 / g; During the acidolysis process, a surfactant is added, which can effectively prevent the agglomeration and sedimentation of the metatitanic acid powder, solubilize the impurities therein, and improve the reaction efficiency of metatitanic acid with sulfuric acid and the complexing agent; the self-made complexing agent added can effectively remove the metal impurities in the metatitanic acid and improve the quality of the titanium dioxide product; during the hydrolysis process, a self-made dispersant is added, which can reduce the agglomeration during the hydrolysis of metatitanic acid and is beneficial to the subsequent formation of titanium dioxide with good dispersion and sphericity.

[0051] 2) The present invention provides a self-made complexing agent containing multiple carboxyl functional groups, which can selectively form stable complexes with impurity ions such as alkali metals and alkaline earth metals in industrial metatitanic acid, significantly increasing the solubility of impurities in acidic solutions, facilitating the efficient separation of impurities from industrial metatitanic acid, and obtaining a purer titanium product. Compared with the traditional strong acid leaching process, the use of this complexing agent can reduce the amount of acid used, lower the risk of environmental pollution, and also play an important role in improving product quality and process efficiency.

[0052] 3) The present invention provides a self-made dispersant. Its glutamic acid side chain contains a large number of carboxylic acid groups, which form carboxylates under alkaline conditions, causing the surface of the metatitanic acid colloidal particles formed after the hydrolysis of titanium oxysulfate to carry negative charges, generating electrostatic repulsion, effectively preventing particles from approaching and aggregating, and improving the dispersion stability. In addition, the π bond of the dopamine side chain can form a coordination bond with the d empty orbital of metal atoms, enabling the dopamine side chain to be firmly adsorbed on the surface of the metatitanic acid colloidal particles. When the amide group in the dopamine side chain approaches the π bond, a larger π bond system is formed due to conjugation, significantly enhancing the adsorption force of the derivative to metal atoms, thereby firmly anchoring the derivative on the surface of the metatitanic acid particles, preventing the loss of the dispersant, and maintaining a stable and lasting dispersion effect. Finally, the spatial structure of the polymer main chain and side chain forms a protective layer on the surface of the colloidal particles, further preventing particle aggregation through the steric hindrance effect, making the finally prepared titanium dioxide have excellent sphericity and dispersibility, and being suitable for high-end application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some schematic diagrams of the embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0054] Figure 1 It is the SEM photograph of the titanium dioxide prepared in Example 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0055] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following will further elaborate on the present invention in combination with embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0056] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through market channels or synthesized from raw materials purchased through market channels.

[0057] A preparation method of a complexing agent includes the following steps:

[0058] 10 mmol of iminodiacetic acid and 4 mmol of potassium carbonate were added to 50 mL of tetrahydrofuran. Under ice bath conditions, 3.1 mmol of trimesoyl chloride (pre-dissolved in 10 mL of tetrahydrofuran) was slowly added dropwise. The addition was completed in 90 min. The reaction was stirred in the ice bath for 1 h. The solvent tetrahydrofuran was removed by rotary evaporation of the product. Then, ethyl acetate was added for extraction and separation, followed by rotary evaporation. The product was recrystallized from ethyl acetate to obtain the complexing agent.

[0059] A method for preparing a dispersant includes the following steps:

[0060] a. 40 mmol of polysuccinimide was dissolved in 15 mL of DMSO to obtain a PSI solution; 15 mmol of dopamine hydrochloride was dissolved in 15 mL of DMSO, and then 12 mL of triethylamine was added. After ultrasonic oscillation for 30 min, a dopamine solution was obtained; the dopamine solution was added to the PSI solution, and the reaction was refluxed at 60 °C under a nitrogen atmosphere for 26 h to obtain a PSI-DA intermediate reaction solution;

[0061] b. 25 mmol of glutamic acid was dissolved in DMSO, and then 14 mL of triethylamine was added. After ultrasonic oscillation for 30 min, a glutamic acid solution was obtained; the glutamic acid solution was added to the intermediate reaction solution, and the reaction was stirred at 60 °C under a nitrogen atmosphere for 16 h. The pH was adjusted to 8 with an aqueous sodium hydroxide solution. The product was precipitated with acetone, filtered, washed with acetone, and dried to obtain the dispersant.

[0062] The present invention will be further described below through specific examples.

[0063] Example 1

[0064] A method for preparing electronic-grade spherical titanium dioxide includes the following steps:

[0065] (1) 100 g of industrial metatitanic acid powder was added to 1000 mL of 98 wt% sulfuric acid solution, and then 2 g of surfactant sodium hexadecylsulfonate and 0.5 g of complexing agent were added. The reaction was heated at 150 °C for 1 h to obtain an acidolysis solution. The acidolysis solution was filtered and diluted with deionized water to obtain a titanium oxysulfate solution with a concentration of 500 g / L (calculated based on the mass of titanium dioxide);

[0066] (2) 30 g of dispersant was added to 1000 mL of titanium oxysulfate solution. The hydrothermal reaction was carried out at 130 °C and 1 MPa for 2 h. After holding and aging for 3 h, a titanium dioxide slurry was obtained;

[0067] (3) 100 g of titanium dioxide slurry was filtered and washed, and then the pH of the system was adjusted to 10 with ammonia water. After stirring and aging for 5 h, 2 g of ammonium sulfate was added. The product was filtered and dried to obtain a powder;

[0068] (4) Bake the powder obtained in step (3) at 900 °C for 3 h, cool it, and grind it to obtain the electronic-grade spherical titanium dioxide, with D 50 being 89 nm and TiO₂ ≥ 99.9 wt%.

[0069] Example 2

[0070] A preparation method of electronic-grade spherical titanium dioxide includes the following steps:

[0071] (1) Add 100 g of industrial metatitanic acid powder to 1000 mL of 95 wt% sulfuric acid solution, then add 1.5 g of surfactant sodium hexadecyl sulfonate and 0.4 g of complexing agent, and heat and react at 130 °C for 2 h to obtain an acidolysis solution. Filter the acidolysis solution and dilute it with deionized water to obtain a titanium oxysulfate solution with a concentration of 400 g / L (calculated based on the mass of titanium dioxide);

[0072] (2) Add 25 g of dispersant to 1000 mL of titanium oxysulfate solution, and perform hydrothermal reaction at 120 °C and 0.8 MPa for 4 h. After holding for aging for 2 h, obtain titanium dioxide slurry;

[0073] (3) Filter and wash 100 g of titanium dioxide slurry, adjust the pH of the system to 9 with ammonia water, stir and age for 4 h, then add 1.5 g of ammonium sulfate. Filter and dry the product to obtain powder;

[0074] (4) Bake the powder obtained in step (3) at 800 °C for 4 h, cool it, and grind it to obtain the electronic-grade spherical titanium dioxide, with D 50 being 75 nm and TiO₂ ≥ 99.9 wt%.

[0075] Example 3

[0076] A preparation method of electronic-grade spherical titanium dioxide includes the following steps:

[0077] (1) Add 100 g of industrial metatitanic acid powder to 1000 mL of 93 wt% sulfuric acid solution, then add 1 g of surfactant sodium hexadecyl sulfonate and 0.3 g of complexing agent, and heat and react at 120 °C for 3 h to obtain an acidolysis solution. Filter the acidolysis solution and dilute it with deionized water to obtain a titanium oxysulfate solution with a concentration of 300 g / L (calculated based on the mass of titanium dioxide);

[0078] (2) Add 20 g of dispersant to 1000 mL of titanium oxysulfate solution, and perform hydrothermal reaction at 110 °C and 0.6 MPa for 8 h. After holding for aging for 2 h, obtain titanium dioxide slurry;

[0079] (3) Filter and wash 100 g of titanium dioxide slurry, adjust the pH of the system to 9 with ammonia water, stir and age for 3 h, then add 1 g of ammonium sulfate. Filter and dry the product to obtain powder;

[0080] (4) Bake the powder obtained in step (3) at 700 °C for 4.5 h, cool it, and grind it to obtain the electronic-grade spherical titanium dioxide, with D 50 being 67 nm and TiO2 ≥ 99.9 wt%.

[0081] Example 4

[0082] A method for preparing electronic-grade spherical titanium dioxide, comprising the following steps:

[0083] (1) Add 100 g of industrial metatitanic acid powder to 1000 mL of 90 wt% sulfuric acid solution, then add 0.5 g of surfactant sodium hexadecyl sulfonate and 0.01 g of complexing agent, and heat and react at 90 °C for 6 h to obtain an acidolysis solution. Filter the acidolysis solution and dilute it with deionized water to obtain a titanium oxysulfate solution with a concentration of 200 g / L (calculated based on the mass of titanium dioxide);

[0084] (2) Add 1 g of dispersant to 1000 mL of titanium oxysulfate solution, and carry out hydrothermal reaction at 90 °C and 0.2 MPa for 12 h. After heat preservation and aging for 1 h, obtain a titanium dioxide slurry;

[0085] (3) Filter and wash 100 g of titanium dioxide slurry, adjust the pH of the system to 8 with ammonia water, stir and age for 2 h, then add 0.5 g of ammonium sulfate, filter and dry the product to obtain a powder;

[0086] (4) Bake the powder obtained in step (3) at 700 °C for 5 h, cool it, and grind it to obtain the electronic-grade spherical titanium dioxide, with D 50 being 73 nm and TiO2 ≥ 99.9 wt%.

[0087] Figure 1 is the SEM photograph of the titanium dioxide prepared in Example 4.

[0088] As mentioned above, the above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing electronic grade spherical titanium dioxide, characterized in that: The steps include: (1) adding industrial metatitanic acid powder to a sulfuric acid solution, then adding a surfactant and a complexing agent, heating to react, obtaining an acid hydrolyzate, filtering and diluting the acid hydrolyzate to obtain a titanyl sulfate solution; (2) adding a dispersant to a titanyl sulfate solution, performing a hydrolysis reaction, and obtaining a titanium dioxide slurry after heat preservation and aging; (3) filtering and washing the titanium dioxide slurry, adjusting the pH, stirring and aging, adding ammonium sulfate, filtering and drying the product to obtain a powder; (4) calcining, cooling, and grinding the powder obtained in step (3) to obtain the electronic grade spherical titanium dioxide; In step (1), the structural formula of the complexing agent is as follows: Specifically, in step (1), the preparation method of the complexing agent comprises the following steps: Adding iminodiacetic acid and potassium carbonate to tetrahydrofuran, slowly adding trimesoyl chloride dropwise under ice bath conditions, stirring to react under ice bath conditions, rotary evaporating the product to remove the solvent tetrahydrofuran, then adding ethyl acetate for extraction and separation, rotary evaporating, and recrystallizing the product in ethyl acetate to obtain the complexing agent; The molar ratio of the iminodiacetic acid, potassium carbonate and trimesoyl chloride is 1:2.5-4:2-3.1; the trimesoyl chloride is added dropwise over 30-90 minutes, and the stirring reaction condition is 0-5°C for 1-6 hours; Specifically, in step (2), the method for preparing the dispersant comprises the following steps: a. Dissolve polysuccinimide in DMSO to obtain a PSI solution; dissolve dopamine hydrochloride in DMSO, then add triethylamine, and perform ultrasonic oscillation to obtain a dopamine solution; The dopamine solution was added to the PSI solution, and the mixture was refluxed under a nitrogen atmosphere to obtain a PSI-DA intermediate reaction solution; b. Dissolve glutamic acid in DMSO, then add triethylamine, and perform ultrasonic oscillation to obtain a glutamic acid solution; Adding the glutamic acid solution to the intermediate reaction solution, stirring the reaction under a nitrogen atmosphere, adjusting the pH with an aqueous sodium hydroxide solution, precipitating the product with acetone, filtering, washing with acetone, and drying to obtain the dispersant; In step a, the dosage ratio of PSI, dopamine hydrochloride and triethylamine is 40mmol:10-15mmol:8-16mL; the ultrasonic oscillation time is 10-30min; the reflux reaction conditions are reflux reaction at 50-70°C for 18-30h; In step b, the ratio of glutamic acid to triethylamine is 30 mmol: 10-20 mL; the stirring reaction conditions are 50-70° C. for 12-20 h, and after the reaction, the pH is adjusted to 7-8; The molar ratio of polysuccinimide, dopamine hydrochloride and glutamic acid is 40:10-15:30-25; In step (1), the concentration of the sulfuric acid solution is 85-98wt%; the dosage ratio of industrial metatitanic acid powder to sulfuric acid solution is 1g:2-10mL; the dosage of the surfactant and the complexing agent are 0.5-2wt% and 0.01-0.5wt% of the industrial metatitanic acid powder, respectively; In step (2), the conditions for the hydrolysis reaction are hydrothermal reaction at 90-130° C. and 0.2-1 MPa for 2-12 h, and heat preservation and aging for 1-3 h.

2. The preparation method according to claim 1, characterized in that: In step (1), the surfactant is one or more of anionic surfactant and nonionic surfactant; the heating reaction condition is 90-150° C. for 1-6 hours; after the reaction, the acid hydrolyzate is diluted with deionized water to obtain a titanyl sulfate solution with a concentration of 200-500 g / L.

3. The preparation method according to claim 1, characterized in that: In step (2), the dosage ratio of the dispersant to the titanyl sulfate solution is 0.1-3 g:100 mL.

4. The preparation method according to claim 1, characterized in that: In step (3), the pH of the system is adjusted to 8-10 with aqueous ammonia, and the mixture is stirred and aged for 2-5 hours. The mass ratio of titanium dioxide slurry to ammonium sulfate is 100:0.5-2.

5. The preparation method according to claim 1, characterized in that: In step (4), calcination is performed at 500-1000° C. for 2-5 hours.

6. An electronic grade spherical titanium dioxide prepared by the preparation method according to any one of claims 1 to 5.

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