A method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization using metatitanic acid

Abstract

This invention discloses a method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization using metatitanic acid, belonging to the field of inorganic materials technology. The method includes: taking crude metatitanic acid obtained from the hydrolysis of titanium liquid using the sulfuric acid method, washing it, mixing it with water to obtain a metatitanic acid slurry, adding a weak base modifier to the metatitanic acid slurry to adjust the pH value to 6.0–7.5, mixing the obtained solid product with water to obtain another slurry, adding dilute acid to the slurry to adjust the pH value to 3.5–5.0, adding a coordination agent and reacting for 40–80 min, washing until the conductivity of the washing solution is ≤100 μS / cm and no sulfate ions are detected, then drying and calcining at 200–380℃ to obtain high-purity titanium dioxide with high specific surface area. This invention achieves ultra-deep desulfurization by using a staged desulfurization process combined with low-temperature structural protection, thus preparing high-purity titanium dioxide with high specific surface area.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials technology, specifically relating to a method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization of metatitanic acid. Background Technology

[0002] As a high-performance white pigment and key semiconductor material, the preparation technology of titanium dioxide directly determines the crystal structure, particle size distribution, surface properties, and application performance of the product, and has a significant impact on the development of photocatalysis, new energy batteries, functional ceramics, and other fields. With the rapid upgrading of the semiconductor industry and the high-end electronic information industry, the market's requirements for the purity, specific surface area, and particle size uniformity of titanium dioxide, a raw material for electronic ceramics, are continuously increasing. Therefore, there is an urgent need to develop methods for preparing high-purity titanium dioxide with high specific surface area.

[0003] Currently, industrial-grade titanium dioxide is mainly produced using the sulfuric acid process. This process is mature, uses readily available raw materials, and has low production costs, making it suitable for large-scale industrial production. However, the metatitanic acid intermediates prepared by the traditional sulfuric acid process contain a large amount of sulfate impurities, with sulfur existing in various forms such as free, surface-adsorbed, lattice-bonded, and pore-encapsulated states. Existing desulfurization processes have the following problems: high-temperature calcination (above 700℃) can achieve deep desulfurization, but it causes titanium dioxide particles to sinter, pores to collapse, and a significant decrease in specific surface area, resulting in a substantial reduction in product activity; room-temperature / medium-temperature water washing and single-alkali washing processes can only remove free and surface-adsorbed sulfate ions, failing to remove lattice-bonded and pore-encapsulated sulfur, resulting in insufficient desulfurization depth and substandard product purity.

[0004] To address the aforementioned issues, researchers in the field have conducted extensive experimental explorations. For example, Chinese patent document CN107298460A discloses a method for producing low-sulfur titanium dioxide with ultra-high specific surface area, which involves adding ammonia water to adjust the pH and heating to 45-50℃ during the salt treatment process. However, this method, relying solely on ammonia water for neutralization, is insufficient to completely remove bonded sulfur deep within the crystal lattice. Chinese patent document CN116924464A discloses a method for preparing nano-high-purity titanium dioxide. This invention reduces the residual amount of various impurities in the metatitanic acid product and improves its purity by controlling the parameter ranges of the water washing and bleaching process and adding an alkaline washing step. However, this invention has a complex system, a lengthy process, and multiple separation steps that result in dispersed titanium resources and a decreased overall yield.

[0005] In summary, there is currently no integrated process that can accurately remove deep sulfur impurities through low-temperature ligand displacement while simultaneously achieving deep desulfurization and high specific surface area retention. Therefore, it is of great significance to develop a mass-producible method for high-purity titanium dioxide with high specific surface area that is compatible with traditional sulfuric acid production lines, operates at low temperature and high efficiency, and can deeply remove lattice sulfur. Summary of the Invention

[0006] To address the issues of incomplete low-temperature desulfurization and significant decrease in specific surface area caused by high-temperature desulfurization in the traditional titanium dioxide sulfuric acid preparation process, this invention provides a method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization of metatitanic acid. This method eliminates the need for high-temperature calcination, maintains controllable low-temperature conditions throughout the process, and achieves deep desulfurization, high purification, and retention of high specific surface area structure of metatitanic acid through specific process combinations and coordination agent replacement methods.

[0007] The specific technical solution adopted is as follows: A method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization using metatitanic acid includes the following steps: (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix it with water to obtain metatitanic acid slurry; (2) Add a weak base modifier to the metatitanic acid slurry and stir to react. Adjust the pH value of the slurry to 6.0-7.5, and then perform solid-liquid separation and wash the solid product. (3) Mix the solid product obtained in step (2) with water to obtain a slurry. Add dilute acid to the slurry to adjust the pH of the system to 3.5 to 5.0. Then add a complexing agent and stir for 40 to 80 min. Then filter and wash until the conductivity of the washing liquid is ≤100μS / cm and no sulfate ions are detected. (4) The product obtained in step (3) is dried and calcined at a low temperature of 200-380℃ to obtain high-purity titanium dioxide with high specific surface area. The ligand is at least one of ethanolamine, oxalic acid, citric acid, disodium EDTA, and sodium gluconate.

[0008] Specifically, the weak base modifier is at least one of ammonia water, ammonium carbonate solution, ammonium bicarbonate solution, and urea solution.

[0009] This invention employs a step-by-step desulfurization process combined with low-temperature structural protection. The first-stage desulfurization process (weak alkali low-temperature neutralization) rapidly removes adsorbed sulfur from the surface of the particles, using a metal-free weak alkali system such as ammonia or ammonium carbonate to avoid introducing secondary pollution caused by metallic impurities such as sodium and potassium. The second-stage desulfurization process (low-temperature dilute acid activation + deep displacement with a coordination agent) opens up the micropores and lattice gaps of the particles through dilute acid activation, and removes deep sulfur impurities with the help of a coordination agent. The coordination agent material can penetrate into the micropores and lattice gaps of the titanium dioxide particles, and through a coordination displacement reaction, replaces the sulfate ions bonded to the titanium hydroxyl groups and encapsulated in the pores, converting the difficult-to-remove deep sulfur impurities into soluble complex salts, which are then removed after washing. Furthermore, this invention maintains a low-temperature environment throughout the process, with the final calcination temperature below 400℃, avoiding particle sintering and pore collapse, thus preserving the original porous structure of titanium dioxide and achieving the preparation of high-purity titanium dioxide with a high specific surface area.

[0010] Specifically, the preparation of crude metatitanic acid by sulfuric acid hydrolysis of titanium liquor can be achieved by the following method: ilmenite is acidified, leached, and reduced to remove impurities using concentrated sulfuric acid to obtain crude titanium liquor; the crude titanium liquor is then subjected to low-temperature crystallization to separate ferrous sulfate, filtered, refined, and concentrated to obtain qualified concentrated titanium liquor; hydrolysis seed crystals are added to the preheated concentrated titanium liquor, and the temperature is raised and maintained to complete the hydrolysis reaction, resulting in the precipitation of metatitanic acid from the sulfuric acid-titanium hydrolysis; the hydrolyzed slurry is then separated by sedimentation and pressure filtration to obtain a solid crude metatitanic acid filter cake, which can be used as the raw material crude metatitanic acid of this invention.

[0011] Preferably, in the process of the present invention, the temperature of the pulp system is maintained at 20-35°C during pulping, pH adjustment and washing.

[0012] Preferably, in step (1), the mass concentration of the metatitanic acid slurry, calculated as titanium dioxide content, is 150-250 g / L.

[0013] Preferably, in step (2), the molar concentration of the weak base modifier is 0.5~3.0 mol / L; the stirring speed is 120~200 r / min, and the time is 20~40 min. The weak base modifier can gently neutralize and remove free sulfate ions physically adsorbed on the particle surface, without introducing any metal impurities throughout the process, thus avoiding secondary pollution. Subsequently, washing removes soluble byproducts such as ammonium sulfate generated in the reaction, preventing salt residue from clogging the pores.

[0014] In step (3), the slurry obtained by mixing the solid product obtained in step (2) with water has a mass concentration of 200-500 g / L based on the titanium dioxide content.

[0015] Preferably, in step (3), the dilute acid is a dilute hydrochloric acid solution or a dilute sulfuric acid solution with a molar concentration of 0.1–2.0 mol / L. The dilute acid treatment is used to activate the micropores and lattice gaps of the metatitanic acid particles, promoting the penetration of the ligand into the particle interior to complete the replacement of sulfur impurities.

[0016] Preferably, in step (3), a complexing agent is added and stirred at 20-35°C for 40-80 min. The amount of complexing agent added is 0.2wt%-5wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is calculated as the titanium dioxide content.

[0017] Preferably, in step (4), the drying conditions are low-temperature drying at 60-80°C until the moisture content is ≤8%, and the low-temperature calcination time is 1-6 h, and more preferably 1-3 h.

[0018] Furthermore, the high-purity titanium dioxide with high specific surface area obtained by the method of the present invention has a purity ≥99.95%, a total sulfur content ≤0.02%, and a specific surface area ≥60 m². 2 / g, with a median particle size D50 of 20–120 nm.

[0019] This invention integrates raw material pre-washing, low-temperature pulping, weak alkali low-temperature modification desulfurization, low-temperature dilute acid activation, deep displacement of complexing agents, and low-temperature molding and calcination into a single process, solving the pain points of traditional processes such as "incomplete low-temperature desulfurization and loss of specific surface area during high-temperature desulfurization." Traditional acid-alkali washing processes can only remove free and adsorbed sulfate ions from the particle surface, failing to remove stable sulfate ions bonded to the crystal lattice and encapsulated in the pores. This is the core reason for excessive sulfur content and insufficient purity in the product. This invention introduces a deep desulfurization system using complexing agents. Under a low-temperature weak acid activation environment, the complexing agent material can penetrate into the micropores and lattice gaps of titanium dioxide particles. Through a complexing displacement reaction, it replaces sulfate ions bonded to titanium hydroxyl groups and encapsulated in the pores, converting the difficult-to-remove deep sulfur impurities into soluble complex salts, which are then thoroughly removed by low-temperature washing. Furthermore, the reaction conditions of this invention are mild and will not damage the titanium dioxide crystal framework and porous structure.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The method of the present invention adopts a step-by-step desulfurization combined with a low-temperature structure protection process, and introduces a low-temperature dilute acid activation + complexing agent deep replacement method, which can achieve ultra-deep desulfurization under low temperature conditions, remove lattice bonding and pore-encapsulated sulfur impurities that cannot be removed by conventional processes, and at the same time does not affect the porous structure of titanium dioxide, thus solving the technical bottleneck of "incomplete low-temperature desulfurization and loss of specific surface area during high-temperature desulfurization".

[0021] (2) The titanium dioxide product prepared by the method of the present invention has intact pores, no agglomeration or collapse, and a specific surface area ≥60 m². 2 / g, total sulfur content ≤0.02%, purity ≥99.95%, excellent performance, high purity, large specific surface area, uniform particle size, and high activity.

[0022] (3) The method of the present invention has strong process adaptability, is green and energy-saving, operates at low temperature throughout the process, has low energy consumption, is suitable for the transformation of existing sulfuric acid process titanium dioxide production lines, does not require the addition of large-scale high-temperature equipment, and the process wastewater is easy to treat, making it suitable for large-scale industrial mass production.

[0023] (4) The titanium dioxide prepared by the method of the present invention has excellent properties, low sulfur impurity content, high purity and large specific surface area, and has broad application prospects in the fields of electronic ceramics, semiconductor components, catalysts and new energy batteries. Attached Figure Description

[0024] Figure 1 This is a SEM image of the titanium dioxide sample prepared in Example 1.

[0025] Figure 2 This is a SEM image of the titanium dioxide sample prepared in Example 2.

[0026] Figure 3This is a SEM image of the titanium dioxide sample prepared in Example 3.

[0027] Figure 4 This is a SEM image of the titanium dioxide sample prepared in Example 4.

[0028] Figure 5 The image shows a SEM image of the titanium dioxide sample prepared in Comparative Example 1. Detailed Implementation

[0029] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0030] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0031] In the following examples and comparative examples, the crude metatitanic acid used was a primary product produced by Ningbo Xinfu Titanium Dioxide Co., Ltd. Alternatively, crude metatitanic acid raw materials obtained through conventional processes in the prior art can also be used. Specifically, crude metatitanic acid can be obtained by the following method: Ilmenite is acidified with concentrated sulfuric acid, leached, and reduced to remove impurities to obtain crude titanium solution; the crude titanium solution is then subjected to low-temperature crystallization to separate ferrous sulfate, filtered, refined, and concentrated to obtain qualified concentrated titanium solution; hydrolyzable seed crystals are added to the preheated concentrated titanium solution, and the temperature is raised and maintained to complete the hydrolysis reaction, resulting in the precipitation of metatitanic acid from the titanium oxysulfate hydrolysate; the hydrolyzed slurry is then separated by sedimentation, pressure filtration, and washing to obtain a solid crude metatitanic acid filter cake, which is the raw material crude metatitanic acid. XRF elemental analysis of the crude metatitanic acid showed a TiO2 content of 93.09% and an SO3 content of 6.90%.

[0032] Example 1 (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 28℃, stir at 160 r / min for 30 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 200 g / L.

[0033] (2) Add 2.0 mol / L ammonia to the metatitanic acid slurry and stir to react. Adjust the pH of the slurry to 7.0, stir at 28℃ for 45 min, and then perform solid-liquid separation. Wash the solid product three times with ultrapure water at 28℃.

[0034] (3) The solid product obtained in step (2) is mixed with water to obtain a slurry. The mass concentration of the slurry is 240 g / L based on the titanium dioxide content. 0.5 mol / L dilute sulfuric acid solution is added to the slurry to adjust the pH of the system to 4.2. Citric acid is then added (the amount added is 1.5 wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is based on the titanium dioxide content). The mixture is stirred at 25°C for 60 min. Then, it is washed at 28°C in multiple countercurrent stages until the conductivity of the washing liquid is 72 μS / cm and no sulfate ions are detected.

[0035] (4) The product obtained in step (3) is dried at 70°C until the moisture content is 7.2%, and then calcined at 300°C for 5 hours to obtain high-purity titanium dioxide with high specific surface area.

[0036] The obtained titanium dioxide was tested, and XRF analysis showed a purity of 99.97%, while a carbon-sulfur analyzer determined the total sulfur content to be 0.015%, and the specific surface area was 156 m². 2 / g, D50=55 nm.

[0037] Example 2 (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 20℃, stir at 200 r / min for 40 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 250 g / L.

[0038] (2) Add 3.0 mol / L ammonium carbonate solution to the metatitanic acid slurry and stir to react. Adjust the pH value of the slurry to 7.5, stir at 20℃ for 60 min, and then perform solid-liquid separation. Wash the solid product three times with ultrapure water at 20℃.

[0039] (3) The solid product obtained in step (2) is mixed with water to obtain a slurry. The mass concentration of the slurry is 300 g / L based on the titanium dioxide content. 0.8 mol / L dilute hydrochloric acid solution is added to the slurry to adjust the pH of the system to 5.0. Then, disodium EDTA (the amount added is 5 wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is based on the titanium dioxide content) is added and stirred at 20℃ for 80 min. Then, the mixture is washed at 20℃ in multiple countercurrent stages until the conductivity of the washing liquid is 81 μS / cm and no sulfate ions are detected.

[0040] (4) The product obtained in step (3) is dried at 60°C until the moisture content is 7.8%, and then calcined at 200°C for 3 hours to obtain high-purity titanium dioxide with high specific surface area.

[0041] The obtained titanium dioxide was tested, and XRF analysis showed a purity of 99.96%, while a carbon-sulfur analyzer determined the total sulfur content to be 0.018%, and the specific surface area was 221 m². 2 / g, D50=24 nm.

[0042] Example 3 (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 35℃, stir at 120 r / min for 20 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 150 g / L.

[0043] (2) Add a mixed solution of ammonium bicarbonate and urea (ammonium bicarbonate concentration is 1.0 mol / L and urea concentration is 1.0 mol / L) to the metatitanic acid slurry, stir and react, adjust the pH of the slurry to 6.0, stir at 35℃ for 30 min, then perform solid-liquid separation, and wash the solid product three times with ultrapure water at 35℃.

[0044] (3) The solid product obtained in step (2) is mixed with water to obtain a slurry. The mass concentration of the slurry is 400 g / L based on the titanium dioxide content. 0.1 mol / L dilute sulfuric acid solution is added to the slurry to adjust the pH of the system to 3.5. Sodium gluconate (the amount added is 0.2 wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is based on the titanium dioxide content) is added. The mixture is stirred at 35°C for 40 min. Then, it is washed at 35°C in multiple countercurrent stages until the conductivity of the washing liquid is 81 μS / cm and no sulfate ions are detected.

[0045] (4) The product obtained in step (3) is dried at 80°C until the moisture content is 6.5%, and then calcined at 380°C for 1 hour to obtain high-purity titanium dioxide with high specific surface area.

[0046] The obtained titanium dioxide was tested, and XRF analysis showed a purity of 99.95%, while a carbon-sulfur analyzer determined the total sulfur content to be 0.020%, and the specific surface area was 192 m². 2 / g, D50=46 nm.

[0047] Example 4 (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 30℃, stir at 180 r / min for 25 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 180 g / L.

[0048] (2) Add 0.5 mol / L urea solution to the metatitanic acid slurry and stir to react. Adjust the pH value of the slurry to 6.5, stir at 30℃ for 50 min, and then perform solid-liquid separation. Wash the solid product three times with 30℃ ultrapure water.

[0049] (3) The solid product obtained in step (2) is mixed with water to obtain a slurry. The mass concentration of the slurry is 300 g / L based on the titanium dioxide content. 0.3 mol / L dilute hydrochloric acid solution is added to the slurry to adjust the pH of the system to 4.0. Then oxalic acid (the amount added is 2wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is based on the titanium dioxide content) is added and stirred at 30°C for 55 min. Then, the mixture is washed at 30°C in multiple countercurrent stages until the conductivity of the washing liquid is 75 μS / cm and no sulfate ions are detected.

[0050] (4) The product obtained in step (3) is dried at 75°C until the moisture content is 7.0%, and then calcined at 370°C for 4 hours to obtain high-purity titanium dioxide with high specific surface area.

[0051] The obtained titanium dioxide was tested, and XRF analysis showed a purity of 99.96%, while a carbon-sulfur analyzer determined the total sulfur content to be 0.016%, and the specific surface area was 150 m². 2 / g, D50=62 nm.

[0052] Comparative Example 1 In this comparative example, titanium dioxide was prepared using a traditional high-temperature calcination process. The specific method is as follows: (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 28℃, stir at 160 r / min for 30 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 200 g / L.

[0053] (2) The metatitanic acid slurry was washed in multiple countercurrent stages until the conductivity of the washing liquid was 72 μS / cm and no sulfate ions were detected.

[0054] (3) The product obtained in step (2) was dried at 70°C until the moisture content was 7.2%, and then calcined at 750°C for 2 hours to obtain a titanium dioxide sample.

[0055] The obtained titanium dioxide was tested, and XRF analysis showed a purity of 99.96%, while a carbon-sulfur analyzer determined the total sulfur content to be 0.015%, and the specific surface area was only 8.5 m². 2 / g, the particle size is between 50~500 nm, and the size varies, making it unsuitable for use in the field of high-end electronic ceramics.

[0056] Comparative Example 2 In this comparative example, titanium dioxide was prepared using a conventional low-temperature, agent-free process. The specific method is as follows: (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix the washed crude metatitanic acid with water at a constant temperature of 30℃, stir at 180 r / min for 25 min to obtain metatitanic acid slurry, the metatitanic acid slurry has a titanium dioxide content of 180 g / L.

[0057] (2) Add 0.5 mol / L urea solution to the metatitanic acid slurry and stir to react. Adjust the pH value of the slurry to 6.5, stir at 30℃ for 50 min, and then perform solid-liquid separation. Wash the solid product three times with 30℃ ultrapure water.

[0058] (3) The product obtained in step (2) was dried at 75°C until the moisture content was 7.0%, and then calcined at 330°C for 2 hours to obtain a titanium dioxide sample.

[0059] Finished product testing: Titanium dioxide XRF test showed a purity of 98.20%, while carbon-sulfur analyzer test showed a total sulfur content of 0.69%. Deep sulfur impurities could not be removed, and the purity did not meet the standard.

[0060] Comparative Example 3 The only difference between the titanium dioxide in this comparative example and Example 4 is that the dilute acid activation step is not performed; all other processes and parameters remain the same, resulting in a titanium dioxide sample.

[0061] Finished product testing indicators: XRF test showed titanium dioxide purity of 98.91%, total sulfur content of 0.44%, and specific surface area of ​​102 m². 2 / g, D50=108 nm.

[0062] Sample Analysis The results above show that, compared with traditional high-temperature processes, the specific surface area of ​​the product of this invention is increased by more than 3 times; compared with conventional low-temperature processes without coordinating agents, the desulfurization accuracy is increased by more than 5 times, and the purity is greatly improved.

[0063] Figures 1-4 The images show SEM images of the high-purity, high-specific-surface-area titanium dioxide prepared in Examples 1-4, respectively. It can be seen that the particles are uniformly dispersed in size, without obvious sintering or agglomeration, and the particle size is concentrated in the range of 20-100 nm. Figure 5 As a comparative example, the traditional high-temperature calcined sample exhibited severe particle sintering, a mixture of large and small particles, and a wide particle size distribution range (50~500 nm).

[0064] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-purity titanium dioxide with high specific surface area based on low-temperature coordination desulfurization using metatitanic acid, characterized in that, Includes the following steps: (1) Take crude metatitanic acid obtained by hydrolysis of titanium liquid by sulfuric acid method, wash it, mix it with water to obtain metatitanic acid slurry; (2) Add a weak base modifier to the metatitanic acid slurry and stir to react. Adjust the pH value of the slurry to 6.0-7.5, and then perform solid-liquid separation and wash the solid product. (3) Mix the solid product obtained in step (2) with water to obtain a slurry. Add dilute acid to the slurry to adjust the pH of the system to 3.5 to 5.

0. Then add a complexing agent and stir for 40 to 80 min. Then filter and wash until the conductivity of the washing liquid is ≤100 μS / cm and no sulfate ions are detected. (4) The product obtained in step (3) is dried and calcined at 200-380°C to obtain high-purity titanium dioxide with high specific surface area. The ligand is at least one of ethanolamine, oxalic acid, citric acid, disodium EDTA, and sodium gluconate.

2. The method according to claim 1, characterized in that, In step (1), the mass concentration of the metatitanic acid slurry, calculated based on the titanium dioxide content, is 150–250 g / L.

3. The method according to claim 1, characterized in that, The weak base modifier is at least one of ammonia water, ammonium carbonate solution, ammonium bicarbonate solution, and urea solution; the molar concentration of the weak base modifier is 0.5 to 3.0 mol / L.

4. The method according to claim 1, characterized in that, In step (3), the mass concentration of the slurry, calculated by titanium dioxide content, is 200-500 g / L.

5. The method according to claim 1, characterized in that, In step (3), the dilute acid is a dilute hydrochloric acid solution or a dilute sulfuric acid solution with a molar concentration of 0.1 to 2.0 mol / L.

6. The method according to claim 1, characterized in that, In step (3), a ligand is added and the mixture is stirred at 20–35°C for 40–80 min.

7. The method according to claim 1, characterized in that, In step (3), the amount of complexing agent added is 0.2wt% to 5wt% of the mass of metatitanic acid in the slurry, and the mass of metatitanic acid is calculated as the titanium dioxide content.

8. The method according to claim 1, characterized in that, In step (4), the drying conditions are 60-80℃ to dry until the moisture content is ≤8%, and the low-temperature calcination time is 1-6 h.

9. The method according to claim 1, characterized in that, The titanium dioxide obtained in step (4) has a purity ≥99.95%, a total sulfur content ≤0.02%, and a specific surface area ≥60 m². 2 / g, with a median particle size D50 of 20–120 nm.

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