Method and system for fluidized synthesis of near-stoichiometric titanium nitride powder

Abstract

The invention discloses a method and a system for fluidized synthesis of near-stoichiometric titanium nitride powder, a trapping agent enters a first-stage low-temperature fluidized bed through a pipeline and a material valve to synthesize TiNCl powder in advance, and then enters a second-stage high-temperature fluidized bed to perform thermal decomposition dechlorination to synthesize the near-stoichiometric titanium nitride powder. The method solves the problem that near-stoichiometric titanium nitride powder is difficult to synthesize due to non-stoichiometric bonding and mass transfer barriers in a traditional synthesis method, is simple in process flow and easy for large-scale production, and has good economic benefits and social benefits.

Description

Technical Field

[0001] The present invention belongs to the fields of materials and chemical engineering, and relates to a method for preparing powders, in particular to a method and system for fluidized synthesis of near-stoichiometric titanium nitride powders. Background Art

[0002] Titanium nitride is a typical non-stoichiometric compound (TiN x ), when the stoichiometric ratio x is between 0.6 and 1.20, it can maintain the face-centered cubic structure. The physical and chemical properties of TiN x are closely related to its stoichiometric ratio x. Usually, only when the stoichiometric ratio x = 1 can the most excellent properties be presented. For example, when x = 1, titanium nitride has the lowest resistivity (about 18 μΩ / cm), the highest hardness (about 28 GPa), and the strongest oxidation resistance. In addition to the stoichiometric ratio, indicators such as the particle size and distribution, chemical purity, phase content, and powder morphology of titanium nitride powders also affect the properties of the material. Generally, high-quality powders need to meet requirements such as fine particle size (0.1 - 2 μm), high purity (>99%), and near-stoichiometry (0.99 < x < 1.01). However, there are still great challenges in synthesizing high-quality titanium nitride powders, especially near-stoichiometric powders.

[0003] Currently, the main methods for synthesizing titanium nitride powders are the carbothermal reduction nitridation method based on TiO2, the direct nitridation method based on titanium powder, and the chemical vapor synthesis method based on TiCl4. Among them, the principle of the carbothermal reduction nitridation method based on TiO2 is to mix TiO2 powder and carbon powder and activate the reducibility of carbon powder at high temperature (1200 - 1800 °C), gradually reducing TiO2 to TiO x and reacting with nitrogen to form TiN (2TiO2 + N2 + 4C = 2TiN + 4CO). However, the TiO2 - C - N2 reaction system path is very complex (Bulletin of the Chinese Ceramic Society, 2000, 19(6): 46 - 49.), with multiple steps in parallel and many by-products, such as Ti2O3, Ti3O4, TiO, and TiC. In addition, due to the difficulty in achieving uniform mixing of TiO2 and C powder during the mixing process, local raw material ratio imbalance occurs, and unreacted TiO2 and free carbon exist in the product. To solve these problems, although currently developed methods for improving material uniformity, such as the coating method and sol - gel method (Ceramics International, 2009, 35(3): 1071 - 1075), and methods for optimizing particle size and enhancing mass transfer through repeated nitridation, have avoided Ti x O yThe product prepared by this method contains high oxygen impurities (~0.6wt.%) and free carbon (~0.8wt.%). It is very difficult to further reduce oxygen impurities and free carbon because the radius of N atoms is not much different from that of C and O atoms, and they are easily dissolved in the TiN lattice and difficult to remove. The stoichiometric ratio is about 0.9.

[0004] The principle of direct nitridation based on titanium powder is that Ti powder directly reacts with N2 at high temperature (1000-1400°C) to form powder (Ti+0.5N2=TiN). In this reaction, due to the existence of an insurmountable mass transfer barrier, the TiN shell initially produced hinders the subsequent diffusion of N2, resulting in residual Ti or Ti2N impurities in the product, and the stoichiometric ratio gradually decreases from the surface to the inside of the powder. The Ti core or Ti2N impurity phase can be eliminated by ball milling titanium powder or TiH2 powder to reduce the particle size to about 5μm or by ball milling the coarse powder containing impurities and then nitriding. However, the ball milling process will introduce oxygen impurities (0.5wt.%) and iron impurities (0.78at.%), and the resulting powder stoichiometric ratio can usually only reach 0.94.

[0005] The principle of the chemical vapor synthesis method based on TiCl4 is to nitride gaseous TiCl4 into TiN at high temperature (TiCl4+N2+H2=TiN+HCl, H2+2TiCl4+2NH3=2TiN+8HCl). Since there is no oxygen element in the system and solid is directly generated in the gas phase, the above-mentioned problems of oxygen impurities and mass transfer barriers can be solved in principle. However, there are two major problems in synthesizing high-quality titanium nitride powder by this reaction. First, due to the low nucleation supersaturation, it is difficult to nucleate in a homogeneous phase. Usually, only a coating can be obtained below 1500°C, but it is difficult to obtain a powder. Second, the reaction path of the system is very complicated, and it is difficult to achieve stoichiometric bonding of titanium and nitrogen elements (The Journal of Physical Chemistry B, 1998, 102(26): 5152-5157). At present, direct synthesis of powders usually adopts high temperature plasma method (High Energy Chemistry, 2016, 50: 466-472). However, due to the uneven temperature of plasma, the stoichiometric ratio of the synthesized powder is difficult to control. 1.1 ) and low stoichiometric ratio (TiN 0.8 ) mixed. In order to simplify the reaction path and reduce the reaction temperature, the U.S. Bureau of Mines proposed a CVD process using Mg vapor as a reducing agent (Metallurgical Transactions B, 1989, 20: 493-497). The principle is to use Mg to reduce TiCl4 to Ti and then nitrided to TiN powder. The equilibrium constant is 10 at 1000°C. 22, solving the problem of difficulty in homogeneous nucleation. After separation and grinding, titanium nitride powder with an average particle size of about 0.28μm was obtained, but the powder contained impurities such as Mg (0.6wt.%), Cl (0.37wt.%), and O (0.55wt.%).

[0006] In view of the above problems, the present invention proposes a system and method for fluidized synthesis of near-stoichiometric titanium nitride powder, which pre-synthesizes stoichiometric TiNCl powder in a first-level low-temperature fluidized bed, and then dechlorinates and synthesizes near-stoichiometric titanium nitride powder in a second-level high-temperature fluidized bed. This solves the problem that near-stoichiometric titanium nitride powder is difficult to synthesize in traditional synthesis methods due to non-stoichiometric bonding and mass transfer barriers. The process flow is simple and easy to scale up for large-scale production. Summary of the invention

[0007] The purpose of the present invention is to provide a system and method for fluidizing the synthesis of nearly stoichiometric titanium nitride powder. The key problem to be solved is the difficulty of synthesizing nearly stoichiometric powder by traditional solid-phase method and gas-phase method due to oxygen solid solution, mass transfer barrier and high homogeneous nucleation energy barrier. A new idea of ​​synthesizing nearly stoichiometric titanium nitride powder by dechlorinating a stoichiometric precursor is proposed. Through graded and zoned reactions, high-quality titanium nitride powder is synthesized in a fluidized bed with high heat and mass transfer efficiency.

[0008] In order to achieve these objectives, the present invention provides a method for fluidizing and synthesizing nearly stoichiometric titanium nitride powder in a first aspect, the method comprising:

[0009] The capture agent captures TiNCl crystal nuclei generated by the reaction of titanium source gas and nitrogen source gas under a fluidized state at 400-530°C and grows into TiNCl powder, and then dechlorinates at above 800°C under a fluidized state, and then separates the capture agent and the nearly stoichiometric titanium nitride powder through a separation process.

[0010] A second aspect of the present invention provides a system for fluidized synthesis of nearly stoichiometric titanium nitride powder, the system comprising:

[0011] Capturing agent feeding device 1, primary low-temperature fluidized bed 2, primary cyclone separation device 3, insulation pipeline 4, secondary high-temperature fluidized bed 5, silo 6, secondary cyclone separation device 7;

[0012] The discharge port of the capture agent feeding device 1 is connected to the feeding port of the first-level low-temperature fluidized bed 2 through a pipeline and a material valve, the bottom feed port of the first-level low-temperature fluidized bed 2 is connected to the titanium source gas, the nitrogen source gas and the inert gas through a pipeline and a gas valve, the gas outlet of the first-level low-temperature fluidized bed 2 is connected to the gas inlet of the first-level cyclone separation device 3 through an insulation pipeline 4, the discharge port of the first-level cyclone separation device 3 is connected to the feed port of the first-level low-temperature fluidized bed 2 through a pipeline, and the gas outlet of the first-level cyclone separation device 3 is connected to the tail gas treatment device;

[0013] The discharge port of the first-level low-temperature fluidized bed 2 is connected to the feed port of the second-level high-temperature fluidized bed 5 through a pipeline and a material valve, the air inlet of the second-level high-temperature fluidized bed 5 is connected to the fluidizing gas through a pipeline and a gas valve, the discharge port of the second-level high-temperature fluidized bed 5 is connected to the silo 6 through a pipeline and a material valve, the air outlet of the second-level high-temperature fluidized bed 5 is connected to the second-level cyclone separation device 7 through a pipeline and a material valve, the discharge port of the second-level cyclone separation device 7 is connected to the feed port of the second-level high-temperature fluidized bed 5 through a pipeline, and the air outlet of the second-level cyclone separation device 7 is connected to the exhaust gas treatment device.

[0014] The third aspect of the present invention provides a method for synthesizing a nearly stoichiometric titanium nitride powder based on the above system, comprising the following steps:

[0015] The capture agent enters the first-level low-temperature fluidized bed 2 through the material valve and pipeline in the capture agent feeding device 1, and the inert gas enters the first-level low-temperature fluidized bed 2 to clean the capture agent. After reaching the reaction temperature, the titanium source gas titanium tetrachloride and the nitrogen source gas ammonia enter the first-level low-temperature fluidized bed 2 to directly synthesize TiNCl based on the gas phase reaction and are captured by the capture agent; the tail gas and part of the fine powder of the first-level low-temperature fluidized bed 2 enter the first-level cyclone separation device 3 through the insulation pipeline 4 to achieve the secondary synthesis of TiNCl and the separation of tail gas and fine powder. The separated fine powder enters the first-level low-temperature fluidized bed 2 again through the pipeline, and the tail gas enters the tail gas treatment device through the outlet of the first-level cyclone separation device 3. After the reaction of the first-level low-temperature fluidized bed 2 is completed, the synthesized TiNCl powder enters the second-level high-temperature fluidized bed 5 through the pipeline and the material valve for dechlorination decomposition reaction. Due to the huge stress caused by the volume shrinkage of thermal decomposition, the synthesized titanium nitride automatically falls off from the surface of the capture agent, and a nearly stoichiometric titanium nitride powder is obtained. Part of the fine powder carried away by the airflow enters the secondary high-temperature fluidized bed 5 again under the action of the secondary cyclone separation device 7. The tail gas generated by the secondary cyclone separation device 7 enters the tail gas treatment device. After the reaction is completed, the powder in the secondary high-temperature fluidized bed 5 enters the silo 6 for storage for subsequent separation.

[0016] One of the characteristics of the present invention is that the synthesis temperature range of TiNCl is 400-530°C; in the system, the temperature range of the first-level low-temperature fluidized bed is controlled at 400-530°C; the above temperature range can specifically be 400°C, 420°C, 430°C, 450°C, 470°C, 480°C, 500°C, 510°C, 530°C and the range between any two of the above values, which can realize the present invention.

[0017] The temperature range of TiNCl powder dechlorination is greater than or equal to 800°C. In the system, the temperature range of the secondary high-temperature fluidized bed is controlled to be greater than or equal to 800°C. The dechlorination temperature here is greater than or equal to 800°C to achieve the purpose of the present invention. When the temperature is above 800°C, the higher the temperature, the higher the efficiency, but the energy consumption will increase accordingly. If the energy consumption needs to be controlled, the dechlorination temperature can be controlled below 1300°C. Preferably, it can be 850°C-950°C.

[0018] The dechlorination reaction time is ≥60 min. The longer the dechlorination reaction time, the higher the efficiency, but the energy consumption also increases. If the energy consumption needs to be controlled, the dechlorination time can be controlled within 200 min, preferably 60-180 min.

[0019] The capture agent is any one of SiO2, Al2O3, ZrO2, KCl, CaCl2, TiN or a mixture of at least two of them.

[0020] The second feature of the present invention is that the separation process includes self-grinding and screening by a ball mill, solution washing and filtering, or centrifugal separation by a centrifuge. Self-grinding by a ball mill does not require the addition of tungsten carbide grinding balls as a ball milling medium.

[0021] The third feature of the present invention is that the temperature of the heat-insulated pipe 4 is controlled to be greater than or equal to 300°C. Here, the purpose of the present invention can be achieved when the temperature of the heat-insulated pipe 4 is greater than or equal to 300°C. When the temperature is above 300°C, the higher the temperature, the higher the efficiency, but the energy consumption will increase accordingly. If the energy consumption needs to be controlled, the temperature of the heat-insulated pipe 4 can be controlled below 600°C. Of course, it is preferred that the temperature of the heat-insulated pipe 4 can be controlled to be 350°C-450°C.

[0022] The fourth feature of the present invention is that the molar ratio of the titanium source gas titanium tetrachloride to the nitrogen source gas ammonia entering the primary low-temperature fluidized bed 2 is ≥1; preferably, the molar ratio is 1-2 and any value therebetween.

[0023] The fifth feature of the present invention is that the carrier gas used for the titanium source gas titanium tetrachloride is an inert gas, and the inlet gas at the bottom of the primary low-temperature fluidized bed is an inert gas, which includes any one of argon, helium, and nitrogen, or a mixture of at least two of them. The inert gas can be used as a cleaning gas for the capture agent, a fluidizing gas, and a raw material carrier gas. The inert gas can be mixed and used in any molar ratio of the above gases.

[0024] The sixth feature of the present invention is that the fluidizing gas of the high temperature fluidized bed is any one of argon, helium, nitrogen, hydrogen, and ammonia, or a mixture of at least two of them. The fluidizing gas can be mixed in any molar ratio of the above gases.

[0025] In the present invention, the synthesis fluidized state of titanium source gas titanium tetrachloride and nitrogen source gas ammonia and the fluidized state of dechlorination can be produced by fluidized bed, and the synthesis fluidized state can preferably be produced by sedimentation fluidized bed.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) High stoichiometric ratio. The conventional solid phase method and gas phase method are difficult to synthesize powders with a near stoichiometric ratio due to the mismatch between mass transfer and reaction, but the present invention can synthesize powders with a near stoichiometric ratio.

[0028] (2) Easy to scale up on an industrial scale. Due to the high efficiency of heat and mass transfer in the fluidized bed and the advantage of continuous material loading and unloading, continuous batch production is possible, which is suitable for industrial scale expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide further explanation of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0030] Figure 1 It is a schematic diagram of the configuration of the system for synthesizing stoichiometric titanium nitride powder of the present invention;

[0031] Figure 2 This is the XRD pattern of the titanium nitride powder obtained in Example 3;

[0032] Figure 3 This is the XRD pattern of the titanium nitride powder obtained in Example 4.

[0033] Reference numerals:

[0034] 1. Capture agent feeding device; 2. First-stage low-temperature fluidized bed; 3. First-stage cyclone separation device; 4. Insulated pipeline; 5. Second-stage high-temperature fluidized bed; 6. Silo; 7. Second-stage cyclone separation device. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0036] Example 1

[0037] Combination Figure 1 , a system for fluidizing and synthesizing nearly stoichiometric titanium nitride powder, the system comprising:

[0038] Capturing agent feeding device 1, primary low-temperature fluidized bed 2, primary cyclone separation device 3, insulation pipeline 4, secondary high-temperature fluidized bed 5, silo 6, secondary cyclone separation device 7;

[0039] The discharge port of the capture agent feeding device 1 is connected to the feeding port of the first-level low-temperature fluidized bed 2 through a pipeline and a material valve, the bottom feed port of the first-level low-temperature fluidized bed 2 is connected to the titanium source gas, the nitrogen source gas and the inert gas through a pipeline and a gas valve, the gas outlet of the first-level low-temperature fluidized bed 2 is connected to the gas inlet of the first-level cyclone separation device 3 through an insulation pipeline 4, the discharge port of the first-level cyclone separation device 3 is connected to the feed port of the first-level low-temperature fluidized bed 2 through a pipeline, and the gas outlet of the first-level cyclone separation device 3 is connected to the tail gas treatment device;

[0040] The discharge port of the first-level low-temperature fluidized bed 2 is connected to the feed port of the second-level high-temperature fluidized bed 5 through a pipeline and a material valve, the air inlet of the second-level high-temperature fluidized bed 5 is connected to the fluidizing gas through a pipeline and a gas valve, the discharge port of the second-level high-temperature fluidized bed 5 is connected to the silo 6 through a pipeline and a material valve, the air outlet of the second-level high-temperature fluidized bed 5 is connected to the second-level cyclone separation device 7 through a pipeline and a material valve, the discharge port of the second-level cyclone separation device 7 is connected to the feed port of the second-level high-temperature fluidized bed 5 through a pipeline, and the air outlet of the second-level cyclone separation device 7 is connected to the exhaust gas treatment device.

[0041] Example 2

[0042] A method for synthesizing nearly stoichiometric titanium nitride powder based on the system described in Example 1 comprises the following steps:

[0043] The capture agent enters the first-level low-temperature fluidized bed 2 through the material valve and pipeline in the capture agent feeding device 1, and the inert gas enters the first-level low-temperature fluidized bed 2 to clean the capture agent. After reaching the reaction temperature, the titanium source gas titanium tetrachloride and the nitrogen source gas ammonia enter the first-level low-temperature fluidized bed 2 to directly synthesize TiNCl based on the gas phase reaction and are captured by the capture agent; the tail gas and part of the fine powder of the first-level low-temperature fluidized bed 2 enter the first-level cyclone separation device 3 through the insulation pipeline 4 to achieve the secondary synthesis of TiNCl and the separation of tail gas and fine powder. The separated fine powder enters the first-level low-temperature fluidized bed 2 again through the pipeline, and the tail gas enters the tail gas treatment device through the outlet of the first-level cyclone separation device 3. After the reaction of the first-level low-temperature fluidized bed 2 is completed, the synthesized TiNCl powder enters the second-level high-temperature fluidized bed 5 through the pipeline and the material valve for dechlorination decomposition reaction. Due to the huge stress caused by the volume shrinkage of thermal decomposition, the synthesized titanium nitride automatically falls off from the surface of the capture agent, and a nearly stoichiometric titanium nitride powder is obtained. Part of the fine powder carried away by the airflow enters the secondary high-temperature fluidized bed 5 again under the action of the secondary cyclone separation device 7. The tail gas generated by the secondary cyclone separation device 7 enters the tail gas treatment device. After the reaction is completed, the powder in the secondary high-temperature fluidized bed 5 enters the silo 6 for storage for subsequent separation.

[0044] Example 3

[0045] In this embodiment, based on the above-mentioned embodiment 2, SiO2 powder with an average particle size of about 40 μm is selected as the capture agent, the reaction temperature of the first-level low-temperature fluidized bed reactor 2 is 450°C, the inert gas is argon, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1, the synthesis time is 30 minutes, the temperature of the insulation pipe 4 is 350°C, the temperature of the second-level high-temperature fluidized bed 5 is 850°C, the fluidizing gas is a mixed gas of ammonia and argon, wherein the molar ratio of ammonia to argon is 1 / 10, the dechlorination time is 60 minutes, and the capture agent and titanium nitride powder are obtained in the silo 6, and the titanium nitride powder is obtained after sieving. Figure 2 The XRD diagram of the obtained powder shows that the powder is a single-phase TiN powder. The unit cell parameter obtained by fitting is 0.4238, indicating that the stoichiometric ratio of the powder is 0.97. Laser particle size analysis shows that the average particle size of the powder is about 10 μm. Chemical purity analysis shows that the purity of the powder is greater than 99%.

[0046] Example 4

[0047] In this embodiment, based on the above-mentioned embodiment 2, Al2O3 powder with an average particle size of about 60 μm and ZrO2 powder with an average particle size of about 100 μm are selected as capture agents, the reaction temperature of the first-level low-temperature fluidized bed reactor 2 is 510°C, the inert gas is argon, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 2, the synthesis time is 120 minutes, the temperature of the insulation pipe 4 is 400°C, the temperature of the second-level high-temperature fluidized bed 5 is 950°C, the fluidizing gas is a mixed gas of hydrogen and argon, wherein the molar ratio of hydrogen to argon is 1 / 5, the dechlorination time is 60 minutes, the capture agent and titanium nitride powder are obtained in the silo 6, and the titanium nitride powder is obtained after sieving. Figure 3 The XRD diagram of the obtained powder shows that the powder is a single-phase TiN powder. The unit cell parameter obtained by fitting is 0.4240nm, indicating that the stoichiometric ratio of the powder is 1.0. Laser particle size analysis shows that the average particle size of the powder is about 15μm. After testing the metal impurity content, the purity of the powder is greater than 99%.

[0048] Example 5

[0049] In this embodiment, based on the above-mentioned embodiment 2, CaCl2 powder with an average particle size of about 200 μm and TiN powder with an average particle size of 100 μm are selected as the capture agent, the reaction temperature of the first-level low-temperature fluidized bed reactor 2 is 420°C, the inert gas is a mixture of argon and helium, the molar ratio is 1, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1.8, the synthesis time is 20 minutes, the temperature of the insulation pipe 4 is 500°C, the temperature of the second-level high-temperature fluidized bed 5 is 850°C, the fluidizing gas is a mixed gas of hydrogen, ammonia and argon, wherein the molar ratio of hydrogen, ammonia and argon is 1 / 1 / 5, the dechlorination time is 160min, the capture agent and titanium nitride powder are obtained in the silo 6, washed and filtered, and the ball mill is self-grinded and then centrifuged to separate the fine powder. The fitting calculation shows that the metering ratio of the powder is 0.98. Laser particle size analysis shows that the average particle size of the powder is about 5 μm. After testing, the purity of the powder after deducting the metal impurity content is greater than 99%.

[0050] Example 6

[0051] In this embodiment, based on the above-mentioned embodiment 2, KCl powder with an average particle size of about 100 μm and SiO2 powder with an average particle size of about 100 μm are selected as the capture agent, the reaction temperature of the first-level low-temperature fluidized bed reactor 2 is 460°C, the inert gas is a mixture of nitrogen and helium, the molar ratio is 2 / 1, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1.6, the synthesis time is 5 minutes, the temperature of the insulation pipe 4 is 420°C, the temperature of the second-level high-temperature fluidized bed 5 is 810°C, the fluidizing gas is a mixed gas of ammonia and nitrogen, wherein the molar ratio of ammonia to nitrogen is 2 / 1, the dechlorination time is 180min, the capture agent and titanium nitride powder are obtained in the silo 6, and the fine powder is separated by water washing, filtration and centrifuge. The fitting calculation shows that the metering ratio of the powder is 0.98. Laser particle size analysis shows that the average particle size of the powder is about 0.8 μm. After testing the metal impurity content, the purity of the powder is greater than 99%.

[0052] The process parameters (such as temperature, time, etc.) of the present invention can realize the method by taking upper and lower limits and interval values, and the embodiments are not listed one by one here.

[0053] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A method for fluidizing and synthesizing nearly stoichiometric titanium nitride powder, the method comprising: The capture agent captures TiNCl crystal nuclei generated by the reaction of titanium source gas titanium tetrachloride and nitrogen source gas ammonia under a fluidized state at 400-530°C and grows them into TiNCl powder, and then dechlorinates at above 800°C under a fluidized state, and then separates the capture agent and nearly stoichiometric titanium nitride powder through a separation process.

2. The method according to claim 1, characterized in that The capture agent is any one of SiO2, Al2O3, ZrO2, KCl, CaCl2, TiN, or a mixture of at least two of them.

3. The method according to claim 1, characterized in that The separation process includes self-grinding screening or solution washing filtration or centrifugal separation.

4. The method according to claim 1, characterized in that: The molar ratio of the titanium source gas to the nitrogen source gas is ≥1.

5. The method according to claim 1, characterized in that The fluidized state is produced by using a fluidized bed.

6. A system for fluidizing and synthesizing nearly stoichiometric titanium nitride powder, characterized in that: The system comprises: Capturing agent feeding device (1), a first-level low-temperature fluidized bed (2), a first-level cyclone separation device (3), a heat-insulating pipeline (4), a second-level high-temperature fluidized bed (5), a silo (6), and a second-level cyclone separation device (7); The discharge port of the capture agent feeding device (1) is connected to the feeding port of the first-level low-temperature fluidized bed (2) through a pipeline and a material valve, the bottom feed port of the first-level low-temperature fluidized bed (2) is connected to the titanium source gas, the nitrogen source gas and the inert gas through a pipeline and a gas valve, the gas outlet of the first-level low-temperature fluidized bed (2) is connected to the gas inlet of the first-level cyclone separation device (3) through an insulation pipeline (4), the discharge port of the first-level cyclone separation device (3) is connected to the feed port of the first-level low-temperature fluidized bed (2) through a pipeline, and the gas outlet of the first-level cyclone separation device (3) is connected to the tail gas treatment device; The discharge port of the primary low-temperature fluidized bed (2) is connected to the feed port of the secondary high-temperature fluidized bed (5) via a pipeline and a material valve, the air inlet of the secondary high-temperature fluidized bed (5) is connected to the fluidizing gas via a pipeline and a gas valve, the discharge port of the secondary high-temperature fluidized bed (5) is connected to the silo (6) via a pipeline and a material valve, the air outlet of the secondary high-temperature fluidized bed (5) is connected to the secondary cyclone separation device (7) via a pipeline and a material valve, the discharge port of the secondary cyclone separation device (7) is connected to the feed port of the secondary high-temperature fluidized bed (5) via a pipeline, and the air outlet of the secondary cyclone separation device (7) is connected to the exhaust gas treatment device.

7. The system according to claim 6, characterized in that The temperature of the heat-insulating pipe (4) is controlled to be greater than or equal to 300°C.

8. The system according to claim 6, characterized in that The inert gas includes any one of argon, helium, and nitrogen, or a mixture of at least two of them.

9. The system according to claim 6, characterized in that The fluidizing gas is any one or more mixed gases of argon, helium, nitrogen, hydrogen and ammonia.

10. The system according to claim 6, characterized in that The tail gas and part of the fine powder generated by the primary low-temperature fluidized bed (2) are used in the primary cyclone separation device (3) to achieve secondary synthesis of TiNCl.

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