A device for preparing titanium dioxide powder, a use method, titanium dioxide powder and applications thereof

Abstract

The application provides a device for preparing titanium dioxide powder, a use method, titanium dioxide powder and application of the titanium dioxide powder. The device comprises: a gas preheating unit for preheating an oxidizing gas; a raw material supply unit for providing gaseous titanium tetrachloride; a water vapor supply unit for providing water vapor; a gas phase mixing unit having a mixing cavity and an inlet and an outlet in communication with the mixing cavity, the inlet being in communication with the outlet of the gas preheating unit and the outlet of the raw material supply unit respectively, and the outlet being in communication with the outlet of the water vapor supply unit; a reaction unit, the inlet of the reaction unit being in communication with the outlet of the gas phase mixing unit, for allowing a gas phase mixture to react to generate titanium dioxide powder; and a product collection unit in communication with the outlet of the reaction unit for collecting the titanium dioxide powder. The application can realize preparation of titanium dioxide powder with controllable particle size, morphology and crystal type ratio.

Description

Technical Field

[0001] This invention belongs to the field of powder material preparation technology, and relates to an apparatus for preparing titanium dioxide powder, a method of using it, titanium dioxide powder and its applications. Background Technology

[0002] Nano-titanium dioxide, due to its small particle size, large specific surface area, high activity, and significant small size and surface effects, has wide applications in photocatalysis, solar cells, coatings, cosmetics, gas sensors, and environmental protection materials. Among them, high-purity, uniformly sized nano-titanium dioxide is a key precursor for the preparation of high-performance electronic ceramics (such as barium titanate), and its particle size distribution directly affects the sintering activity and final properties of subsequent solid-phase synthesis products.

[0003] Furthermore, titanium dioxide powders with different morphologies often exhibit different properties. For example, spherical titanium dioxide has a large specific surface area, good flowability, excellent dispersibility, and high activity. In particular, spherical anatase / rutile mixed-phase titanium dioxide, as a key precursor for the preparation of high-performance electronic ceramics, directly affects the sintering activity and final properties of the subsequent solid-phase synthesis products due to its sphericity and crystal phase composition.

[0004] Currently, gas-phase oxidation is one of the mainstream methods for preparing nano-titanium dioxide, usually using titanium tetrachloride as a precursor, which reacts with oxygen at high temperature to generate titanium dioxide particles. However, existing technologies still generally have the following problems: (1) the product has a wide particle size distribution (D90 / D50 is often greater than 2), poor uniformity, and is not conducive to being used as a precursor powder for homogeneous reactions; (2) the process is complex or difficult to produce continuously; (3) the product is prone to agglomeration, or impurities are introduced to control the particle size, affecting the purity. For example, CN106946288A discloses a method of adding aluminum trichloride as a seed crystal to titanium tetrachloride to control the crystal form, but it introduces aluminum impurities. CN113943015A uses an acoustic field to promote particle agglomeration to optimize the particle size distribution, but the resulting particles are mainly micron-sized agglomerates, which limits its application. CN106865608A solves the problem of preparing anatase titanium dioxide, but the product needs to be scraped from the reactor wall, which makes continuous production impossible, and the particle size distribution is wide.

[0005] The main methods for preparing spherical titanium dioxide include hard template method, soft template method, solvothermal method, spray drying method, and oxyhydrogen flame hydrolysis method. These methods have the following drawbacks: hard template method and soft template method are prone to introducing template impurities, resulting in discontinuous processes and difficulties in large-scale production; solvothermal method has many control variables, complex operation, and poor reproducibility; spray drying method is prone to introducing impurities, clogging nozzles, and particle agglomeration; oxyhydrogen flame hydrolysis method has high equipment requirements, is prone to scaling inside the reactor, and affects continuous operation.

[0006] Therefore, developing a simple, continuous, impurity-free, controllable morphology, particle size and crystal form, and uniform particle size distribution nano-titanium dioxide preparation technology is of great significance for promoting its application in high-end ceramics, catalysis and other fields. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an apparatus for preparing titanium dioxide powder, a method for using it, titanium dioxide powder, and its applications. Using the apparatus and method provided by this invention, the particle size of the product can be precisely controlled within the range of 20 nm to 1 μm, ensuring narrow particle size distribution, good particle dispersibility, and controllable morphology and crystal ratio. Furthermore, the process is simple and suitable for continuous industrial production. The prepared uniform powder is particularly suitable as a raw material for the synthesis of high-quality barium titanate and other electronic ceramics.

[0008] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides an apparatus for preparing titanium dioxide powder, the apparatus comprising: Gas preheating unit, used for preheating oxidizing gases; Raw material supply unit, used to supply gaseous titanium tetrachloride; A steam supply unit is used to provide steam. A gas phase mixing unit has a mixing chamber and an inlet and an outlet communicating with the mixing chamber. The inlet is connected to the outlet of the gas preheating unit and the outlet of the raw material supply unit, respectively, and the outlet is connected to the outlet of the water vapor supply unit. The reaction unit has its inlet connected to the outlet of the gas-phase mixing unit, and is used to cause the gas-phase mixture to react and generate titanium dioxide powder. The product collection unit is connected to the outlet of the high-temperature reaction unit and is used to collect the titanium dioxide powder.

[0009] In this invention, gaseous titanium tetrachloride is mixed with preheated oxidizing gas in a gas-phase mixing unit, and water vapor is introduced. The three then react in a reaction unit to generate titanium dioxide particles, which are finally collected to obtain titanium dioxide powder. This device has a simple structure, good continuity, and does not introduce impurities. Furthermore, by controlling the flow rate of water vapor, selective preparation of titanium dioxide morphology and crystal form ratio (anatase / rutile phase) can be achieved. The obtained titanium dioxide has good flowability and a large specific surface area, showing broad prospects for industrial applications.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] Preferably, the gas preheating unit includes an oxidizing gas input pipeline and a gas preheating furnace connected sequentially along the gas flow direction.

[0012] Preferably, the oxidizing gas input pipeline is equipped with a first gas flow meter.

[0013] Preferably, the raw material supply unit includes a first carrier gas input pipeline and a raw material volatilization tank connected sequentially along the airflow direction; the first carrier gas input pipeline is used to introduce a protective gas; the raw material volatilization tank is used to contain and heat liquid titanium tetrachloride, converting it into gaseous titanium tetrachloride; the gaseous titanium tetrachloride is carried by the protective gas and transported through the outlet of the raw material volatilization tank to the inlet of the gas phase mixing unit.

[0014] Preferably, a second gas flow meter is installed on the first carrier gas input pipeline.

[0015] Preferably, the water vapor supply unit includes a second carrier gas input pipeline and a water vapor evaporator connected sequentially along the airflow direction; the second carrier gas input pipeline is used to introduce a protective gas; the water vapor evaporator is used to contain and heat liquid water to convert it into water vapor; the water vapor is carried by the protective gas and transported through the outlet of the water vapor evaporator to the inlet of the gas phase mixing unit.

[0016] Preferably, a third gas flow meter is installed on the second carrier gas input pipeline.

[0017] Preferably, the reaction unit includes a tubular furnace and a reaction tube disposed within the furnace chamber of the tubular furnace.

[0018] Preferably, the number of reaction tubes is at least one, and more preferably two to four.

[0019] Preferably, the inner diameter of the tubular furnace chamber is 20mm~300mm, such as 20mm, 50mm, 100mm, 150mm, 200mm, 250mm or 300mm, and the length of the reaction zone is 550mm~650mm, such as 550mm, 570mm, 600mm, 620mm or 650mm.

[0020] Preferably, the length of the tubular furnace chamber is 1000mm to 1400mm, such as 1000mm, 1100mm, 1200mm, 1300mm or 1400mm.

[0021] Preferably, the inner diameter of each reaction tube is 20mm to 70mm, for example, 20mm, 30mm, 40mm, 50mm, 60mm or 70mm.

[0022] In this invention, the use of one or more reaction tubes with relatively small inner diameters effectively limits the concentration and temperature gradient within the reaction zone, promoting uniform nucleation and growth of particles, thereby obtaining powders with an extremely narrow particle size distribution (D90 / D50 < 2.5). Furthermore, multiple reaction tubes can form a honeycomb-like pipe structure, further enhancing mixing and heat transfer. In addition, the reaction tubes do not scale when water vapor is introduced, maintaining production safety and demonstrating potential for industrial applications.

[0023] Preferably, the product collection unit includes a dry collection device or a wet collection device.

[0024] It is understood that the aforementioned wet collection device generally refers to equipment that can pass reaction products into a liquid medium for collection. This can involve directly introducing the products into water or other liquids for collection, or integrating subsequent processing units to separate the products from the liquid phase into powder through centrifugation, filtration, or other methods. Preferably, a water bath collection followed by solid-liquid separation and drying is employed, thereby effectively suppressing particle agglomeration while achieving efficient collection.

[0025] Preferably, the dry collection device includes any one or a combination of at least two of the following: a cyclone separator, a bag filter, or an electrostatic precipitator.

[0026] In a second aspect, the present invention provides a method of using the device as described in the first aspect, the method of use comprising: (1) The oxidizing gas is preheated in the gas preheating unit and then output to the inlet of the gas phase mixing unit; (2) Liquid titanium tetrachloride is first heated to a gaseous state in the raw material supply unit and then output to the inlet of the gas phase mixing unit; (3) Mix the preheated oxidizing gas with gaseous titanium tetrachloride in the mixing chamber of the gas phase mixing unit; (4) The liquid water is heated to steam in the water supply unit and then output to the outlet of the reaction unit; (5) The gas-phase mixture is introduced into the inlet of the reaction unit from the outlet of the gas-phase mixing unit, and titanium dioxide powder is generated after the reaction; (6) Collect the titanium dioxide powder into the product collection unit.

[0027] In this invention, by controlling conditions such as gas flow rate and reaction temperature, the morphology, particle size, and crystal composition of the product can be controlled. In particular, when other preparation parameters remain unchanged, selective preparation of spherical or square morphologies can be achieved simply by adjusting the water vapor flow rate, and the ratio of anatase phase to rutile phase can be continuously adjusted between 0 and 1; and the product particle size can be quantitatively controlled within the range of 20 nm to 1 μm simply by adjusting the flow rate of the oxidizing gas.

[0028] However, if water vapor is directly introduced into liquid titanium tetrachloride, the highly heterogeneous gas-liquid interface can easily lead to an excess of water vapor in localized areas. This heterogeneous mixing triggers a violent, uncontrolled hydrolysis reaction, generating complex and inconsistent titanium dioxide precursors. During subsequent calcination, these structurally diverse precursors make it difficult to precisely control the particle size distribution and crystal phase structure of the final product. Furthermore, this process is cumbersome and difficult to scale up for continuous production.

[0029] Preferably, the oxidizing gas in step (1) includes oxygen. For example, the oxidizing gas may be oxygen, air, a mixture of oxygen and air, or oxygen diluted with an inert gas.

[0030] Preferably, the preheating cutoff temperature in step (1) is 200℃~900℃, such as 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃ or 900℃.

[0031] Preferably, in step (2), liquid titanium tetrachloride is first heated to a gaseous state in the raw material volatilization tank and then carried out by the protective gas introduced through the first carrier gas input pipeline.

[0032] Preferably, the cutoff temperature of the first heating temperature in step (2) is 20℃~200℃, such as 20℃, 50℃, 80℃, 100℃, 120℃, 150℃, 180℃ or 200℃.

[0033] Preferably, in step (4), liquid water is heated to water vapor in a water vapor evaporation tank and then carried out by a protective gas introduced through a second carrier gas input pipeline.

[0034] Preferably, the protective gas includes nitrogen and / or argon.

[0035] Preferably, the cutoff temperature of the second heating in step (4) is 50℃~150℃, such as 50℃, 80℃, 100℃, 120℃ or 150℃.

[0036] It is understandable that when the temperature of the first or second heating is low, the carrier gas can be directly introduced below the liquid surface, and the liquid reactants can be output through bubbling.

[0037] Preferably, in each reaction tube of the reaction unit in step (5), the flow rate of the oxidizing gas is 1L / min to 10L / min, for example, 1L / min, 2L / min, 4L / min, 6L / min, 8L / min or 10L / min, the flow rate of the first carrier gas is 0.1L / min to 1L / min, for example, 0.1L / min, 0.2L / min, 0.3L / min, 0.5L / min, 0.8L / min or 1L / min, and the flow rate of the gaseous titanium tetrachloride is 0.1g / min to 0.6g / min, for example, 0.1g / min, 0.2g / min, 0.3g / min, 0.4g / min, 0.5g / min or 0.6g / min.

[0038] In this invention, when other conditions (such as reaction temperature, gaseous titanium tetrachloride flow rate, and water vapor flow rate) remain constant, the average particle size of the powder initially decreases and then increases with increasing oxidizing gas flow rate. This is because, within a certain range, increasing the oxidizing gas flow rate helps increase nucleation centers in the reaction system and shortens the residence time, thereby reducing the final particle size. However, as the oxidizing gas flow rate continues to increase, the contact time between gaseous reactants becomes shorter, resulting in incomplete reaction and the formation of agglomerates between particles, which in turn increases the particle size. Therefore, by simply adjusting the oxidizing gas flow rate entering the gas preheating unit to within the range of 1 L / min to 10 L / min, controllable preparation of titanium dioxide powder with an average particle size in the range of 20 nm to 1 μm can be achieved.

[0039] Preferably, in each reaction tube of the reaction unit in step (5), the flow rate of the second carrier gas is 0 L / min to 10 L / min, but does not include 0 L / min, for example 0.00001 L / min, 0.0001 L / min, 0.001 L / min, 0.01 L / min, 0.1 L / min, 1 L / min, 2 L / min, 4 L / min, 6 L / min, 8 L / min or 10 L / min, etc.; the flow rate of the water vapor is 0 g / min to 1 g / min, but does not include 0 g / min, for example 0.0001 g / min, 0.001 g / min, 0.01 g / min, 0.1 g / min, 0.3 g / min, 0.5 g / min, 0.8 g / min or 1 g / min, etc.

[0040] It should be noted that in this invention, the flow rates of gaseous titanium tetrachloride and water vapor can be adjusted by the flow rates of the first carrier gas and the second carrier gas, respectively, and the flow rates of the first and second carrier gases can be monitored by the second and third gas flow meters, respectively. For example, when the required flow rate of the oxidizing gas in each reaction tube is 2 L / min, and there are 3 reaction tubes, it is only necessary to ensure that the reading of the first gas flow meter is 6 L / min.

[0041] Preferably, the reaction temperature in step (5) is 950℃~1200℃, for example 950℃, 1000℃, 1050℃, 1100℃, 1150℃ or 1200℃.

[0042] Preferably, when the flow rate of water vapor in each reaction tube of the reaction unit in step (5) is <0.05 g / min, the morphology of the titanium dioxide powder is square; when the flow rate of water vapor is 0.05 g / min to 1 g / min, the morphology of the titanium dioxide powder is spherical.

[0043] In this invention, the introduction of water vapor can lower the nucleation barrier of the reaction system, promote uniform gas phase nucleation, and prevent particles from preferentially depositing on the tube wall. Therefore, the greater the flow rate of water vapor, the more likely it is to form spherical particles and prevent the reaction tube from scaling.

[0044] Furthermore, the flow rate of water vapor also affects the ratio of anatase and rutile phases in the titanium dioxide powder product. When the flow rates of the oxidizing gas, the first carrier gas, the gaseous titanium tetrachloride, and the reaction temperature in step (5) remain constant, the proportion of the anatase phase in the titanium dioxide powder gradually decreases as the water vapor flow rate increases. For example, when the water vapor flow rate approaches 0, titanium dioxide powder with an anatase phase content of 100% can be prepared.

[0045] Thirdly, the present invention provides a titanium dioxide powder prepared by the method described in the second aspect.

[0046] Preferably, the average particle size of the titanium dioxide powder is 20nm~1μm, such as 20nm, 30nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 800nm ​​or 1μm, and more preferably 30nm~500nm.

[0047] Preferably, the particle size distribution of the titanium dioxide satisfies D90 / D50<2.5, for example, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3 or 2.4, etc.

[0048] Fourthly, the present invention also provides an application of the titanium dioxide powder as described in the third aspect in the fields of photocatalysis, coatings, electronic ceramics, or cosmetics.

[0049] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0050] Compared with the prior art, the present invention has the following beneficial effects: 1. Controllable morphology and high purity: Spherical or square particles can be selectively prepared by simply adjusting the flow rate of water vapor. The entire process is a gas-phase reaction, requiring no templates or additives, resulting in high product purity. 2. Particle size and crystal form can be precisely controlled: By adjusting simple parameters such as gas flow rate, the product particle size can be adjusted in the range of 20nm to 1μm, and the ratio of anatase phase to rutile phase can be continuously adjusted. 3. Continuous process and easy to scale up: The equipment has a reasonable structure and a short process flow, making it suitable for large-scale continuous production; 4. The reactor does not scale and operates stably: The introduction of water vapor can effectively inhibit the deposition on the tube wall and improve the long-term stability of the equipment. 5. Wide range of applications: The resulting powder has a narrow particle size distribution (D90 / D50 < 2.5), good particle dispersibility, and minimal agglomeration. This highly uniform powder is an ideal precursor for homogeneous solid-phase reactions (such as the synthesis of barium titanate). It is suitable for multiple fields such as photocatalysis, coatings, and electronic ceramics. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the device provided by the present invention.

[0052] Figure 2 This is a schematic diagram of the structure of multiple small-diameter reaction tubes arranged in parallel in the reactor of Example 1.7 (A is a side view, B is a top view).

[0053] Figure 3 This is a schematic diagram of the structure of multiple small-diameter reaction tubes arranged in parallel in the reactor of Example 2.7 (A is a side view, B is a top view).

[0054] Figure 4 This is a scanning electron microscope (SEM) image of the titanium dioxide powder prepared in Example 1.1.

[0055] Figure 5 This is a SEM image of the titanium dioxide powder prepared in Example 1.2.

[0056] Figure 6This is a SEM image of the titanium dioxide powder prepared in Example 1.9.

[0057] Figure 7 This is a SEM image of the titanium dioxide powder prepared in Example 2.1.

[0058] Figure 8 This is a SEM image of the titanium dioxide powder prepared in Example 2.2.

[0059] Figure 9 This is a SEM image of the titanium dioxide powder prepared in Example 2.3.

[0060] Figure 10 This is the X-ray diffraction (XRD) pattern of the titanium dioxide powder prepared in Example 1.1.

[0061] Figure 11 This is the XRD pattern of the titanium dioxide powder prepared in Example 1.2.

[0062] Figure 12 This is the XRD pattern of the titanium dioxide powder prepared in Example 1.3.

[0063] Figure 13 This is the XRD pattern of the titanium dioxide powder prepared in Example 2.1.

[0064] Figure 14 This is the XRD pattern of the titanium dioxide powder prepared in Example 2.2.

[0065] Figure 15 This is the XRD pattern of the titanium dioxide powder prepared in Example 2.3.

[0066] Figure 1 In the middle section: 1-Gas preheating unit; 11-Oxidizing gas input pipeline; 111-First gas flow meter; 12-Gas preheating furnace; 2-Raw material supply unit 2; 21-First carrier gas input pipeline; 211-Second gas flow meter; 22-Raw material evaporation tank; 3-Water vapor supply unit; 31-Second carrier gas input pipeline; 311-Third gas flow meter; 32-Water vapor evaporation tank; 4-Gas phase mixing unit; 5-Reaction unit; 6-Product collection unit. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0068] "The scope of this invention can be defined by a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower limit and upper limit values ​​can be arbitrarily combined to form a new range. That is, any lower limit value can be combined with any upper limit value to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then 1~3, 1~4, and 2~3, 1~4, 2~5 ... All ranges from 1 to 5, 2 to 3, 2 to 4, and 2 to 5 fall within the scope of this invention. In this invention, the numerical range "a to b" represents a shortened representation of any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between 0 and 5 have been fully listed in this document; "0 to 5" is merely a shortened representation of this numerical combination. When a parameter is expressed as an integer ≥ 2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, and 10. When a parameter is expressed as an integer selected from "2 to 10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0069] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0070] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0071] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0072] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0073] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0074] Example 1.1 This embodiment provides an apparatus for preparing titanium dioxide powder, such as... Figure 1 As shown, the system includes: a gas preheating unit 1 (including an oxidizing gas input pipeline 11 and a gas preheating furnace 12, with a first gas flow meter 111 installed on the oxidizing gas input pipeline 11), a raw material supply unit 2 (including a first carrier gas input pipeline 21 and a raw material volatilization tank 22, with a second gas flow meter 211 installed on the first carrier gas input pipeline 21), a water vapor supply unit 3 (including a second carrier gas input pipeline 31 and a water vapor volatilization tank 32, with a third gas flow meter 311 installed on the second carrier gas input pipeline 31), a gas phase mixing unit 4, a reaction unit 5 (furnace inner diameter 60mm, one quartz reaction tube with an inner diameter of 20mm and a wall thickness of 1mm), and a product collection unit 6. The usage method is as follows: (1) Oxygen is fed into the gas preheating furnace 12 at a flow rate of 5L / min and preheated at 900℃, and then output to the inlet of the gas phase mixing unit 4; (2) In the raw material volatilization tank 22, the liquid titanium tetrachloride is heated to gaseous state at 150°C and carried out by N2 introduced through the first carrier gas input line 21 to the inlet of the gas phase mixing unit 4 (N2 flow rate 0.4L / min, gaseous titanium tetrachloride flow rate about 0.22g / min). (3) Mix the preheated oxygen with gaseous titanium tetrachloride in the mixing chamber of the gas phase mixing unit 4; (4) In the water vapor evaporation tank 32, the liquid water is heated to water vapor at 110°C and carried out by N2 introduced through the second carrier gas input pipeline 31 to the outlet of the reaction unit 4 (N2 flow rate 1L / min, water vapor flow rate about 0.1g / min). (5) The gaseous mixture is introduced into the inlet of the reaction unit 5 from the outlet of the gas mixing unit 4 and reacted at 1050°C to generate titanium dioxide powder. (6) Collect the titanium dioxide powder into the product collection unit 6 (wet collection device), filter the suspension after water bath collection, and dry the filter cake in an oven at 80°C for 12 hours.

[0075] Example 1.2 The difference between this embodiment and embodiment 1.1 is that in step (4), the N2 flow rate is adjusted to 3L / min and the water vapor flow rate is about 0.2g / min; The remaining preparation methods and parameters are consistent with those in Example 1.1.

[0076] Example 1.3 The difference between this embodiment and embodiment 1.2 is that in step (1), the oxygen flow rate is adjusted to 7L / min, and in step (4), the N2 flow rate is adjusted to 2L / min, and the water vapor flow rate is about 0.16g / min; The remaining preparation methods and parameters are consistent with those in Example 1.2.

[0077] Example 1.4 The difference between this embodiment and embodiment 1.1 is that in step (5), the reaction temperature is adjusted to 950°C; The remaining preparation methods and parameters are consistent with those in Example 1.1.

[0078] Example 1.5 The difference between this embodiment and embodiment 1.4 is that in step (4), the N2 flow rate is adjusted to 3L / min and the water vapor flow rate is about 0.2g / min; The remaining preparation methods and parameters are consistent with those in Example 1.4.

[0079] Example 1.6 The difference between this embodiment and embodiment 1.5 is that in step (1), the oxygen flow rate is adjusted to 2L / min; The remaining preparation methods and parameters are consistent with those in Example 1.5.

[0080] Example 1.7 The difference between this embodiment and embodiment 1.1 is that, as Figure 2 As shown, three quartz reaction tubes are arranged in parallel in reaction unit 5. Each reaction tube has an inner diameter of 20 mm and a wall thickness of 1 mm, and the flow rate of gaseous reactants in each reaction tube remains constant. The remaining preparation methods and parameters are consistent with those in Example 1.1.

[0081] Example 1.8 The difference between this embodiment and embodiment 1.1 is that the oxygen flow rate in step (1) is 10 L / min, the N2 flow rate in step (2) is 0.1 L / min, and the gaseous titanium tetrachloride flow rate is 0.1 g / min. The remaining preparation methods and parameters are consistent with those in Example 1.1.

[0082] Example 1.9 The difference between this embodiment and embodiment 1.1 is that the oxygen flow rate in step (1) is 1L / min, the N2 flow rate in step (2) is 1L / min, the gaseous titanium tetrachloride flow rate is 0.6g / min, and the N2 flow rate in step (4) is 10L / min and the water vapor flow rate is 1g / min. The remaining preparation methods and parameters are consistent with those in Example 1.1.

[0083] Example 2.1 This embodiment provides an apparatus for preparing titanium dioxide powder, comprising: a gas preheating unit 1 (including an oxidizing gas input pipeline 11 and a gas preheating furnace 12, and a first gas flow meter 111 installed on the oxidizing gas input pipeline 11), a raw material supply unit 2 (including a first carrier gas input pipeline 21 and a raw material volatilization tank 22, and a second gas flow meter 211 installed on the first carrier gas input pipeline 21), a water vapor supply unit 3 (including a second carrier gas input pipeline 31 and a water vapor volatilization tank 32, and a third gas flow meter 311 installed on the second carrier gas input pipeline 31), a gas phase mixing unit 4, a reaction unit 5 (a quartz tube with a furnace inner diameter of 60 mm, a single inner diameter of 20 mm, and a wall thickness of 1 mm), and a product collection unit 6. The method of use is as follows: (1) Oxygen is fed into the gas preheating furnace 12 at a flow rate of 8L / min, preheated at 900℃, and then output to the inlet of the gas phase mixing unit 4; (2) In the raw material volatilization tank 22, the liquid titanium tetrachloride is heated to gaseous state at 150°C and carried out by N2 introduced through the first carrier gas input line 21 to the inlet of the gas phase mixing unit 4 (N2 flow rate 0.4L / min, gaseous titanium tetrachloride flow rate about 0.22g / min). (3) Mix the preheated oxygen with gaseous titanium tetrachloride in the mixing chamber of the gas phase mixing unit 4; (4) In the water vapor evaporation tank 32, the liquid water is heated to water vapor at 110°C and carried out by N2 introduced through the second carrier gas input pipeline 31 to the outlet of the reaction unit 4 (N2 flow rate 0.01L / min, water vapor flow rate about 0.01g / min). (5) The gaseous mixture is introduced into the inlet of the reaction unit 5 from the outlet of the gas mixing unit 4 and reacted at 1050°C to generate titanium dioxide powder. (6) Collect the titanium dioxide powder into the product collection unit 6 (wet collection device), filter the suspension after water bath collection, and dry the filter cake in an oven at 80°C for 12 hours.

[0084] Example 2.2 The difference between this embodiment and embodiment 2.1 is that in step (1), the oxygen flow rate is adjusted to 2L / min; The remaining preparation methods and parameters are consistent with those in Example 2.1.

[0085] Example 2.3 The difference between this embodiment and embodiment 2.1 is that in step (1), the oxygen flow rate is adjusted to 5 L / min; The remaining preparation methods and parameters are consistent with those in Example 2.1.

[0086] Example 2.4 The difference between this embodiment and embodiment 2.1 is that in step (2), the N2 flow rate is 0.8 L / min, the gaseous titanium tetrachloride flow rate is about 0.45 g / min, and in step (5), the reaction temperature is adjusted to 950 °C. The remaining preparation methods and parameters are consistent with those in Example 2.1.

[0087] Example 2.5 The difference between this embodiment and embodiment 2.4 is that in step (1), the oxygen flow rate is adjusted to 5 L / min, and in step (2), the N2 flow rate is adjusted to 0.4 L / min, and the mass flow rate of titanium tetrachloride is about 0.22 g / min. The remaining preparation methods and parameters are consistent with those in Example 2.4.

[0088] Example 2.6 The difference between this embodiment and embodiment 2.5 is that in step (1), the oxygen flow rate is adjusted to 2L / min; The remaining preparation methods and parameters are consistent with those in Example 2.5.

[0089] Example 2.7 The difference between this embodiment and embodiment 2.1 is that, as Figure 3 As shown, two quartz reaction tubes with an inner diameter of 20 mm and a wall thickness of 1 mm are arranged side by side in the reactor of reaction unit 5, and the flow rate of gaseous reactants in each reaction tube is kept constant. The remaining preparation methods and parameters are consistent with those in Example 2.1.

[0090] Example 2.8 The difference between this embodiment and embodiment 2.1 is that in step (4), the N2 flow rate is adjusted to 0.04 L / min and the water vapor flow rate is 0.04 g / min; All other preparation methods and parameters remained the same.

[0091] Performance testing The titanium dioxide powders prepared in Examples 1.1-1.9 and Examples 2.1-2.8 were subjected to SEM, XRD, particle size, and particle size distribution tests. The test results are as follows: Figures 4-15 As shown in Tables 1 and 2.

[0092] Table 1 Table 2 It should be noted that in the products obtained in Examples 1.1-1.9 and Examples 2.1-2.8 below, the sum of the proportions of anatase phase and rutile phase is 100%. Therefore, the proportion of the other phase can be calculated from the proportion of one phase shown in Tables 1 and 2. For example, in Example 1.1 in Table 1, the proportion of anatase phase is 70%, so the proportion of rutile phase can be calculated to be 30%.

[0093] Figures 4-15 The data in Tables 1 and 2 show that, under the apparatus and method provided by this invention, by adjusting the oxygen flow rate, water vapor mass flow rate, and reaction temperature, titanium dioxide powders with different morphologies, average particle sizes, and crystal phase ratios can be stably and reproducibly prepared. Furthermore, the particle size distribution index (D90 / D50) of all products is less than 2.5. Especially when the prepared product is square titanium dioxide, its particle size distribution is even narrower, with D90 / D50 all below 1.8, and as low as 1.4 in Example 2.3, demonstrating its excellent uniformity. This highly uniform powder lays a solid foundation for subsequent solid-phase synthesis of electronic ceramic materials such as barium titanate with uniform composition and excellent performance. Simultaneously, even with proportionally increased gas flow rate and number of reaction tubes, powders with uniform particle size and consistent performance can still be stably prepared, and the total yield is effectively improved, indicating that the apparatus can be stably scaled up.

[0094] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An apparatus for preparing titanium dioxide powder, characterized in that, The device includes: Gas preheating unit, used for preheating oxidizing gases; Raw material supply unit, used to supply gaseous titanium tetrachloride; A steam supply unit is used to provide steam. A gas phase mixing unit has a mixing chamber and an inlet and an outlet communicating with the mixing chamber. The inlet is connected to the outlet of the gas preheating unit and the outlet of the raw material supply unit, respectively, and the outlet is connected to the outlet of the water vapor supply unit. The reaction unit has its inlet connected to the outlet of the gas-phase mixing unit, and is used to cause the gas-phase mixture to react and generate titanium dioxide powder. The product collection unit is connected to the outlet of the reaction unit and is used to collect the titanium dioxide powder.

2. The apparatus according to claim 1, characterized in that, The gas preheating unit includes an oxidizing gas input pipeline and a gas preheating furnace connected sequentially along the gas flow direction; Preferably, the oxidizing gas input pipeline is equipped with a first gas flow meter; Preferably, the raw material supply unit includes a first carrier gas input pipeline and a raw material volatilization tank connected sequentially along the airflow direction; the first carrier gas input pipeline is used to introduce a protective gas; the raw material volatilization tank is used to contain and heat liquid titanium tetrachloride, converting it into gaseous titanium tetrachloride; the gaseous titanium tetrachloride is carried by the protective gas and transported through the outlet of the raw material volatilization tank to the inlet of the gas phase mixing unit; Preferably, a second gas flow meter is installed on the first carrier gas input pipeline; Preferably, the water vapor supply unit includes a second carrier gas input pipeline and a water vapor evaporation tank connected sequentially along the airflow direction; the second carrier gas input pipeline is used to introduce a protective gas; the water vapor evaporation tank is used to contain and heat liquid water, converting it into water vapor; the water vapor is carried by the protective gas and transported through the outlet of the water vapor evaporation tank to the inlet of the gas phase mixing unit; Preferably, a third gas flow meter is installed on the second carrier gas input pipeline.

3. The apparatus according to claim 2, characterized in that, The reaction unit includes a tubular furnace and a reaction tube disposed inside the furnace chamber of the tubular furnace; Preferably, the number of reaction tubes is at least one, more preferably two to four; Preferably, the inner diameter of the tubular furnace chamber is 20mm~300mm, and the length of the reaction zone is 550mm~650mm; Preferably, the inner diameter of each reaction tube is 20mm to 70mm; Preferably, the product collection unit includes a dry collection device or a wet collection device; Preferably, the dry collection device includes any one or a combination of at least two of the following: a cyclone separator, a bag filter, or an electrostatic precipitator.

4. A method of using the apparatus as described in any one of claims 1-3, characterized in that, The method of use includes: (1) The oxidizing gas is preheated in the gas preheating unit and then output to the inlet of the gas phase mixing unit; (2) Liquid titanium tetrachloride is first heated to a gaseous state in the raw material supply unit and then output to the inlet of the gas phase mixing unit; (3) Mix the preheated oxidizing gas with gaseous titanium tetrachloride in the mixing chamber of the gas phase mixing unit; (4) The liquid water is heated to steam in the water supply unit and then output to the outlet of the reaction unit; (5) The gas-phase mixture is introduced into the inlet of the reaction unit from the outlet of the gas-phase mixing unit, and titanium dioxide powder is generated after the reaction; (6) Collect the titanium dioxide powder into the product collection unit.

5. The method of use according to claim 4, characterized in that, The oxidizing gas in step (1) includes oxygen; Preferably, the preheating cutoff temperature in step (1) is 200℃~900℃; Preferably, in step (2), liquid titanium tetrachloride is first heated to a gaseous state in the raw material volatilization tank and then carried out by the protective gas introduced through the first carrier gas input pipeline; Preferably, the cutoff temperature of the first heating in step (2) is 20℃~200℃; Preferably, in step (4), liquid water is heated to water vapor in a water vapor evaporation tank and then carried out by a protective gas introduced through a second carrier gas input pipeline; Preferably, the cutoff temperature of the second heating in step (4) is 50℃~150℃.

6. The method of use according to claim 4 or 5, characterized in that, In each reaction tube of the reaction unit described in step (5), the flow rate of the oxidizing gas is 1 L / min to 10 L / min, the flow rate of the first carrier gas is 0.1 L / min to 1 L / min, and the flow rate of the gaseous titanium tetrachloride is 0.1 g / min to 0.6 g / min. Preferably, in each reaction tube of the reaction unit in step (5), the flow rate of the second carrier gas is 0 L / min to 10 L / min, but not including 0 L / min; the flow rate of the water vapor is 0 g / min to 1 g / min, but not including 0 g / min; Preferably, the reaction temperature in step (5) is 950℃~1200℃.

7. The method of use according to claim 6, characterized in that, When the flow rate of water vapor in each reaction tube of the reaction unit in step (5) is <0.05 g / min, the morphology of the titanium dioxide powder is square; when the flow rate of water vapor is 0.05 g / min to 1 g / min, the morphology of the titanium dioxide powder is spherical.

8. A titanium dioxide powder prepared by the method according to any one of claims 4-7.

9. The titanium dioxide powder according to claim 8, characterized in that, The average particle size of the titanium dioxide powder is 20 nm to 1 μm. Preferably, the average particle size of the titanium dioxide powder is 30 nm to 500 nm; Preferably, the particle size distribution of the titanium dioxide powder satisfies D90 / D50<2.

5.

10. The application of the titanium dioxide powder as described in claim 8 or 9 in the fields of photocatalysis, coatings, electronic ceramics or cosmetics.

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