Method for preparing super-dispersed rutile-type nano titanium dioxide powder by one-step hydrothermal method

Abstract

The present invention belongs to the technical field of inorganic nano-powder materials, and discloses a method for preparing super-dispersed rutile-type nano titanium dioxide powder by a one-step hydrothermal method. Specifically, using a titanium salt as a raw material, a rutile-type nano titanium dioxide slurry is obtained through multiple hydrothermal processes at different temperatures, and then the super-dispersed rutile-type nano titanium dioxide powder is prepared by washing and drying. Through the high-temperature and high-pressure synthesis reaction process of the hydrothermal method, the present invention replaces the high-temperature calcination process for traditional preparation of rutile-type titanium dioxide powder, not only solving the problems of particle agglomeration and growth caused by the calcination process, but also simplifying the process route and saving energy. In addition, the particles formed by the hydrothermal method form crystal nuclei with ions as the center and grow, so the rutile-type titanium dioxide particles prepared by the present invention are smaller in size and more uniformly dispersed.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic nano powder materials, and specifically relates to a method for preparing super-dispersed rutile nano titanium dioxide powder by a one-step hydrothermal method. Background Art

[0002] As a polycrystalline compound of a wide-bandgap semiconductor, nano titanium dioxide powder is widely used in nano-electronic functional ceramics, photocatalysis, coatings, cosmetics and other fields due to its large specific surface area, high catalytic activity and small particle size. In nature, titanium dioxide mainly exists in three forms, namely anatase type, rutile type and brookite type. Rutile titanium dioxide has become the most widely used crystal form due to its good chemical stability and thermal stability.

[0003] In existing reports, rutile nano titanium dioxide powder is usually prepared by sol-gel method, microemulsion method, hydrolysis method and high-temperature gas-phase reaction method. For example, tetrabutyl titanate is used as raw material, absolute ethanol as solvent, glacial acetic acid as stabilizer, and hydrochloric acid as catalyst to prepare TiO2 sol. After aging the sol, TiO2 gel is obtained and calcined at high temperature to finally obtain rutile nano titanium dioxide powder. This method has a complex process flow, expensive raw materials and solvents, and uses dangerous chemicals such as concentrated hydrochloric acid, resulting in high cost, difficult operation and environmental hazards, so it is extremely difficult to industrialize. In addition, the calcination process will cause rapid aggregation of nano particles and the degree is uncontrollable, so it is difficult to obtain uniformly dispersed and fine rutile nano titanium dioxide powder by this method. Another example is to use titanium tetrachloride as raw material, add it to pure water, hydrolyze the raw material, and obtain nano hydrated titanium dioxide by controlling the hydrolysis conditions, and finally obtain rutile nano titanium dioxide powder by high-temperature calcination. Although this method greatly simplifies the process flow, it still requires a high-temperature calcination process, and has disadvantages such as large particles, serious aggregation, poor uniformity and low production efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies existing in the prior art and provide a method for preparing super-dispersed rutile-type nano titanium dioxide powder by a one-step hydrothermal method. Using the principle of hydrolysis reaction, with a titanium salt as the reaction raw material, by controlling the temperature and time of the hydrothermal process, multiple-step hydrolysis occurs for the raw materials in an aqueous environment to generate rutile-type nano titanium dioxide. After the slurry is washed and dried, the nano titanium dioxide powder is obtained. In the process of the hydrolysis reaction to form a precipitate, crystal nuclei are formed and grow with ions as the center. Therefore, the formed crystal nuclei are uniform and fine, so that the finally obtained powder has a smaller size and a more uniform morphology. At the same time, multiple hydrothermal processes at different temperatures also make the particle size distribution of the finally prepared powder more uniform and easier to control. The present invention only involves the hydrothermal process, with high efficiency, energy saving, environmental friendliness, and high synthesis conversion rate, fully meeting the usage requirements of the electronics industry.

[0005] To solve the above technical problems, the present invention provides a method for preparing super-dispersed rutile-type nano titanium dioxide powder by a one-step hydrothermal method, including the following steps:

[0006] (1) Add pure water into a hydrothermal reaction kettle;

[0007] (2) Add an organic dispersant;

[0008] (3) Slowly add the titanium salt solution into the reaction kettle;

[0009] (4) First, start the reaction kettle and stir at 20 - 30 °C for 0.5 - 2 h, then heat up to 70 - 90 °C at a rate of 0.5 - 1 °C / min, keep warm for 1 - 3 h, and add a crystal form control agent. Then heat up to 190 - 230 °C at a rate of 5 - 10 °C / min and keep warm for 2 - 5 h to obtain a rutile-type nano titanium dioxide slurry. Finally, after washing and drying, super-dispersed rutile-type nano titanium dioxide particle powder is obtained;

[0010] In step (2), the addition ratio of the organic dispersant is 1 - 5%;

[0011] The concentration of the titanium salt solution described in step (3) is 40 - 80%, and the volume of the titanium salt solution is 8 - 50% of the volume of the pure water;

[0012] In step (4), the addition ratio of the crystal form control agent is 0.1 - 0.5%.

[0013] Specifically, the organic dispersant described in step (2) is polyacrylamide, polyethylene glycol, or cellulose and its derivatives; the titanium salt described in step (3) is titanium tetrachloride, titanium oxysulfate, or titanium oxychloride; the crystal form control agent described in step (4) is polymethacrylic acid, ethylenediaminetetraacetic acid, or stearic acid.

[0014] The beneficial effects that can be achieved by the present invention are as follows: The present invention only drives the multi-step hydrolysis reaction of titanium salts through the hydrothermal process, and the process of forming a precipitate by hydrolysis reaction forms crystal nuclei centered on ions and grows. Therefore, the formed crystal nuclei are uniform, dispersed and fine, so that the rutile-type nano-titanium dioxide powder prepared by the present invention has a smaller size (radial size 30 nm), a more uniform morphology and a narrower particle size distribution (D 50 : 0.08 - 0.1 um); no high-temperature calcination step is involved in the process, avoiding the phenomenon of large particles and uneven particles caused by nanoparticle agglomeration, and at the same time simplifying the process flow and making large-scale production easier to achieve. The present invention only involves the hydrothermal process, with high efficiency, energy saving, environmental friendliness and high synthesis conversion rate, fully meeting the usage requirements of downstream industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the preparation principle of rutile-type titanium dioxide powder in Example 1.

[0016] Figure 2 It is the SEM image of the nano-rutile-type titanium dioxide powder prepared in Example 1.

[0017] Figure 3 It is the XRD pattern of the nano-rutile-type titanium dioxide powder prepared in Example 2.

[0018] Figure 4 It is the PSA pattern of the nano-rutile-type titanium dioxide powder prepared in Example 2.

[0019] Figure 5 It is the calculation result diagram of the average grain size of the nano-rutile-type titanium dioxide powder prepared in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following examples can further clearly understand the present invention, but they do not limit the present invention.

[0021] Example 1

[0022] A method for preparing super-dispersed rutile-type nano-titanium dioxide powder by one-step hydrothermal method, comprising the following steps:

[0023] (1) Add 50 L of pure water to the hydrothermal reactor;

[0024] (2) Add 3.5% of polyacrylamide and stir until the solution is clear;

[0025] (3) Slowly add 15 L of titanium oxychloride solution with a concentration of 65% to the reactor;

[0026] (4) Start the stirring of the reaction kettle. After stirring for 1 h at 25 °C, heat it up to 80 °C at a heating rate of 0.75 °C / min and keep it warm for 2 h. Then add 0.3% of polymethacrylic acid, and further heat it up to 200 °C at a rate of 7 °C / min. After keeping it warm for 4 h, cool it naturally to room temperature to obtain rutile-type nano-titanium dioxide slurry. Subsequently, wash it with pure water and dry it to obtain rutile-type nano-titanium dioxide powder.

[0027] From the preparation principle of rutile-type titanium dioxide powder ( Figure 1 ) it can be seen that in the mixed solution of organic dispersant and titanium salt, Ti 4+ is evenly adsorbed on the long-chain molecules of the organic dispersant. Therefore, during the nucleation process, the crystal nuclei are not prone to agglomeration, and the obtained powder has a more uniform morphology and better dispersibility. In addition, the titanium dioxide particles form crystal nuclei with ions as the center and grow, so they also have small size.

[0028] From the SEM image of the prepared nano-rutile-type titanium dioxide powder ( Figure 2 ) it can be seen that under the SEM photo with a magnification of 60,000 times, the titanium dioxide powder is composed of short needle-like particles with good dispersibility and uniform size. There is no obvious agglomeration phenomenon or large particles, indicating that the rutile-type nano-titanium dioxide powder prepared in this example has good uniformity and dispersibility, and the particles have a small size (the radial size is about 30 nm).

[0029] Example 2

[0030] A method for preparing super-dispersed rutile-type nano-titanium dioxide powder by one-step hydrothermal method, comprising the following steps:

[0031] (1) Add 80 L of pure water to the hydrothermal reaction kettle;

[0032] (2) Add 1% of ethyl cellulose and stir until the solution is clear;

[0033] (3) Slowly add 6.4 L of titanyl sulfate solution with a concentration of 80% to the reaction kettle;

[0034] (4) Start the stirring of the reaction kettle. After stirring for 2 h at 20 °C, heat it up to 90 °C at a rate of 0.5 °C / min and keep it warm for 1 h. Then add 0.1% of ethylenediaminetetraacetic acid, and further heat it up to 230 °C at a rate of 5 °C / min. After keeping it warm for 2 h, cool it naturally to room temperature to obtain rutile-type nano-titanium dioxide slurry. Then wash it with pure water and dry it to obtain rutile-type nano-titanium dioxide powder.

[0035] Figure 3 The XRD pattern of the rutile-type nano-titanium dioxide powder prepared in this example. From Figure 3It can be seen that the diffraction curve of the titanium dioxide powder is smooth, with high peak intensity and narrow half-peak width, indicating that the rutile-type nano-titanium dioxide powder prepared in this example has good crystallinity.

[0036] Figure 4 This is the particle size test result of the rutile-type nano-titanium dioxide powder prepared in this example. Figure 4 It can be seen that the titanium dioxide powder has the advantages of narrow particle size distribution (D 50 : 106 nm; D 100 : 344 nm), indicating that the prepared powder has good uniformity and dispersibility.

[0037] Example 3

[0038] A method for preparing super-dispersed rutile-type nano-titanium dioxide powder by a one-step hydrothermal method, comprising the following steps:

[0039] (1) Add 60 L of pure water to a hydrothermal reaction kettle;

[0040] (2) Add 5% polyethylene glycol and stir until the solution is clear;

[0041] (3) Slowly add 30 L of a 40% titanium oxychloride solution to the reaction kettle;

[0042] (4) Start stirring the reaction kettle. After stirring at 30 °C for 0.5 h, raise the temperature to 70 °C at a rate of 1 °C / min and keep it warm for 3 h. Add 0.5% stearic acid, then raise the temperature to 190 °C at a rate of 10 °C / min, keep it warm for 5 h, and then naturally cool to room temperature to obtain a rutile-type nano-titanium dioxide slurry. Subsequently, wash it with pure water and dry it to obtain rutile-type nano-titanium dioxide powder.

[0043] Figure 5 This is the calculation result of the average size of the titanium dioxide powder prepared in Example 3. Figure 5 It is obtained that the average size of the rutile-type nano-titanium dioxide particles prepared in Example 3 is 24 nm This is basically consistent with Figure 2 the conclusion obtained.

[0044] The above is only the best implementation mode of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several deformations or equivalent replacements can be made to the technical solution of the present invention, and the same technical effects can also be achieved, which should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing super-dispersed rutile-type nano-titanium dioxide powder by a one-step hydrothermal method, characterized in that, It includes the following steps: (1) Add pure water into a hydrothermal reactor; (2) Add an organic dispersant; (3) Slowly add a titanium salt solution into the reactor; (4) First, start the reactor and stir at room temperature for 0.5 - 2 h, then heat it up to 70 - 90 °C at a rate of 0.5 - 1 °C / min, keep it warm for 1 - 3 h, add a crystal form control agent, heat it up to 190 - 230 °C at a rate of 5 - 10 °C / min and keep it warm for 2 - 5 h, then rutile-type nano-titanium dioxide slurry can be obtained. Finally, after washing and drying, super-dispersed rutile-type nano-titanium dioxide particle powder can be obtained; In step (2), the addition ratio of the organic dispersant is 1 - 5%, and the organic dispersant described in step (2) is polyacrylamide, polyethylene glycol or cellulose and its derivatives; In step (3), the concentration of the titanium salt solution is 40 - 80%, and the volume of the titanium salt solution is 8 - 50% of the volume of pure water; In step (4), the addition ratio of the crystal form control agent is 0.1 - 0.5%, and the crystal form control agent described in step (4) is polymethacrylic acid, ethylenediaminetetraacetic acid or stearic acid.

2. The method for preparing super-dispersed rutile-type nano-titanium dioxide powder by hydrothermal method according to claim 1, characterized in that: The titanium salt described in step (3) is titanium tetrachloride, titanium oxysulfate or titanium oxychloride.

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