Method and system for fluidized synthesis of TiNCl powder

Abstract

The invention discloses a method and a system for fluidized synthesis of TiNCl powder. The method comprises the following steps: fully exposing the surface of a trapping agent in a fluidized bed, trapping TiNCl crystal nucleuses separated out based on a gas phase reaction of TiCl4 and NH3 in a specific temperature range, depositing and growing into TiNCl powder, and finally, grinding or cleaning to separate out the TiNCl powder. According to the method, the problems of long synthesis time, harsh conditions and low efficiency of a traditional precursor conversion method are solved, meanwhile, the problem that powder is difficult to obtain due to small supersaturation degree of a reaction system is solved, the technological process is simple, large-scale production is easy to achieve, and good economic benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the field of materials and chemical industry, relates to the preparation of powder, and specifically relates to a method and system for fluidized synthesis of TiNCl powder. Background Art

[0002] TiNCl is a metal nitrogen halide with a sandwich layered structure, in which the Ti-N layer has a strong covalent bond and exhibits electronic conductivity, while the Ti-Cl layer is bound by van der Waals forces, forming a polyhedral channel that can not only store hydrogen but also provide Li + 、Na + Mg + It provides a fast channel for storage and transportation, thus attracting widespread attention in the fields of superconductivity, energy storage and photocatalysis. Recently, TiNCl is considered to be a very promising new generation of metal ion battery materials (Journal of Energy Storage, 2024, 78, 110105). However, the efficient synthesis of TiNCl still faces great difficulties, which hinders its practical application from laboratory to industry.

[0003] Currently, the synthesis of TiNCl is mainly based on the precursor conversion method of TiCl4 and NH3, that is, first in a horizontal or vertical reactor, gaseous or liquid TiCl4 and NH3 react under the protection of inert gas to generate a primary precursor mixture (Mater. Res. Bull., 2022, 153, 111896; Sci. China. Mater. 2022, 65(11): 2942–2948; J. Mater. Chem., 2009, 19, 2573–2582). Since the reaction path of TiCl4 and NH3 is very complicated, there are many parallel reactions, and it is very sensitive to temperature. Due to the low heat and mass transfer efficiency in horizontal and vertical reactors, there are many by-products, including TiCl3(NH2), TiCl2(NH2)2, TiCl(NH2)3, TiCl4·xNH3, TiCl3(NH2), TiCl(NH2)3, (NH4)2TiCl6 and NH4Cl, etc., and it is very difficult to synthesize TiNCl in a directional manner. In order to remove the by-products, the primary precursor needs to be calcined at 400°C in flowing NH3 for 3 to 10 hours to obtain a secondary precursor mixed powder. Finally, the secondary precursor is mixed with a small amount of NH4Cl and sealed in a high vacuum quartz tube, and placed in a horizontal furnace with a temperature gradient and heated for 1 to 3 weeks (J.Electrochem.Soc., 2004, 151, A843). The powder is purified by chemical vapor transport migration to obtain high-crystallinity TiNCl. ​​This method is very time-consuming and has a low yield. The reported maximum single-time laboratory yield is about 200 mg (Condens. Matter., 2022, 7, 33). Recently, Tanaka et al. (ACS Omega 2022, 7, 6375-6380) proposed the use of NaNH2 as a nitrogen source to synthesize TiNCl. ​​First, TiCl4 and NaNH2 are frozen with liquid nitrogen and sealed in a high vacuum glass tube. Then, the sealed glass tube is gradually heated to 150°C within 12 hours and kept warm for 1 to 2 days to obtain a primary powder. The primary powder is then sealed in a quartz tube and calcined at 400°C to 230°C for 1 day to obtain TiNCl powder. Because the raw materials are flammable and explosive, and the reaction releases huge heat, the synthesis conditions are very harsh, and there are still great difficulties in actual production.

[0004] In view of the above problems, the present invention proposes a method and system for fluidized synthesis of TiNCl powder, discovers a new synthesis temperature range and synthesis path, develops an efficient synthesis method, and realizes one-step synthesis of TiNCl powder on the surface of a capture agent in a fluidized bed, avoiding the problems of long synthesis time, harsh conditions and low efficiency of the traditional precursor conversion method, and at the same time solves the problem of difficulty in obtaining powder due to the low supersaturation of the reaction system, and the process flow is simple and easy to scale up. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for fluidized synthesis of TiNCl powder. The key problem to be solved is that the reaction path of TiCl4 and NH3 is complex, there are many by-products, and the temperature-sensitive characteristics of the product composition do not match the existing reactor, making it difficult to efficiently and directionally synthesize TiNCl powder. A new process for efficient and directional synthesis of TiNCl powder is proposed, in which a capture agent is used to capture TiNCl crystal nuclei synthesized by one-step vapor deposition within a specific temperature range in a fluidized bed with high heat and mass transfer efficiency and grow them into TiNCl powder.

[0006] In order to achieve these objectives, the present invention provides a method for fluidizing and synthesizing TiNCl powder in a first aspect, the method comprising:

[0007] 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 the capture agent and TiNCl powder are separated through a separation process.

[0008] The second aspect of the present invention provides a system for fluidized synthesis of TiNCl powder, the system comprising a capture agent feeding device 1, a sedimentation fluidized bed 2, a powder collecting device 3, a cyclone separation device 4, and an insulation pipe 5.

[0009] The discharge port of the capture agent feeding device 1 is connected to the feed port of the sedimentation fluidized bed 2 through a pipeline and a feed valve; the bottom feed port of the sedimentation fluidized bed 2 is connected to the titanium source gas, nitrogen source gas and inert gas through pipelines and gas valves; the discharge port of the sedimentation fluidized bed 2 is connected to the feed port of the powder collection device 3 through pipelines and a feed valve; the air outlet of the sedimentation fluidized bed 2 is connected to the air inlet of the cyclone separation device 4 through an insulation pipeline 5; the discharge port of the cyclone separation device 4 is connected to the feed port of the sedimentation fluidized bed 2 through a pipeline; the air outlet of the cyclone separation device 4 is connected to the exhaust gas treatment device.

[0010] The present invention also provides a method for fluidizing and synthesizing TiNCl powder based on the above system from a third aspect, comprising the following steps:

[0011] The capture agent enters the deposition fluidized bed 2 through the material valve and pipeline in the capture agent feeding device 1. The inert gas first enters the deposition 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 deposition 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 deposition fluidized bed 2 enter the cyclone separation device 4 through the insulation pipeline 5 to achieve the secondary synthesis of TiNCl and the separation of tail gas and fine powder. The separated fine powder enters the deposition fluidized bed 2 again through the pipeline, and the tail gas enters the tail gas treatment device through the outlet of the cyclone separation device 4. After the reaction is completed, the TiNCl powder synthesized in the deposition fluidized bed 2 enters the powder collection device 3 through the pipeline and the material valve to obtain the target powder. The target powder is then separated from the capture agent and TiNCl powder through a separation process, and the capture agent returns to the capture agent feeding device 1 for reuse, and the TiNCl powder is used as a product.

[0012] 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 deposition 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.

[0013] The capture agent can be selected from any one of SiO2, Al2O3, LiCl, NaCl, KCl, CaCl2 or a mixture of at least two thereof.

[0014] 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.

[0015] The third feature of the present invention is that the temperature of the heat-insulated pipe 5 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 5 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 5 can be controlled below 600°C. Of course, it is preferred that the temperature of the heat-insulated pipe 5 can be controlled to be 350°C-450°C.

[0016] 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 is ≥1, preferably, the molar ratio is 1-2 and any value therebetween.

[0017] 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 deposition fluidized bed is an inert gas, which includes any one of argon, helium, and nitrogen, or a mixed gas of at least two. 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.

[0018] In the present invention, the synthesis fluidized state of titanium source gas titanium tetrachloride and nitrogen source gas ammonia can be produced by a fluidized bed, preferably a sedimentary fluidized bed.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) Simple process flow. The traditional precursor conversion method requires precursor synthesis, precursor heat treatment, precursor purification and other steps to obtain powder. The present invention is directly based on gas phase one-step synthesis, which significantly shortens the process flow.

[0021] (2) High synthesis efficiency. The traditional process takes about 3 weeks to synthesize 200 mg of sample at a time, and the synthesis efficiency is about 3.9×10 -4 g.h -1 , while the small-scale reactor in the laboratory of this process only takes about 60 minutes (10g·h -1 ), not only the output is large but also the time is short, and the synthesis efficiency is improved by about 5 orders of magnitude.

[0022] (3) Easy to scale up on an industrial scale. The traditional precursor conversion method uses a horizontal tube or vertical tube reactor with low heat and mass transfer efficiency, which is difficult to operate continuously and has a significant scale-up effect, making it difficult to scale up industrially. The present invention uses a fluidized bed reaction system, which not only solves the problem of the reaction system being sensitive to temperature and the complex reaction path, but also solves the problem of the difficulty in homogeneous nucleation to obtain powder. It can be produced in batches continuously and is suitable for industrial scale-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 1 It is a schematic diagram of the configuration of the system for synthesizing TiNCl powder of the present invention;

[0025] Figure 2 The XRD pattern of TiNCl powder obtained in Example 3;

[0026] Figure 3 This is the SEM image of the TiNCl powder obtained in Example 4.

[0027] Reference numerals:

[0028] 1. Capturing agent feeding device; 2. Sedimentation fluidized bed; 3. Powder collecting device; 4. Cyclone separation device; 5. Insulation pipeline. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0030] Example 1

[0031] Combination Figure 1 The system for fluidized synthesis of TiNCl powder used in this embodiment includes a capture agent feeding device 1, a sedimentation fluidized bed 2, a powder collecting device 3, a cyclone separation device 4, and an insulation pipeline 5;

[0032] The discharge port of the capture agent feeding device 1 is connected to the feed port of the sedimentation fluidized bed 2 through a pipeline and a feed valve; the bottom feed port of the sedimentation fluidized bed 2 is connected to the titanium source gas, nitrogen source gas and inert gas through pipelines and gas valves; the discharge port of the sedimentation fluidized bed 2 is connected to the feed port of the powder collection device 3 through pipelines and a feed valve; the air outlet of the sedimentation fluidized bed 2 is connected to the air inlet of the cyclone separation device 4 through an insulation pipeline 5; the discharge port of the cyclone separation device 4 is connected to the feed port of the sedimentation fluidized bed 2 through a pipeline; the air outlet of the cyclone separation device 4 is connected to the exhaust gas treatment device.

[0033] Example 2

[0034] This embodiment uses the method for synthesizing TiNCl powder in the system of embodiment 1, which specifically includes the following steps:

[0035] The capture agent enters the deposition fluidized bed 2 through the material valve and pipeline in the capture agent feeding device 1. The inert gas first enters the deposition 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 deposition 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 deposition fluidized bed 2 enter the cyclone separation device 4 through the insulation pipeline 5 to achieve the secondary synthesis of TiNCl and the separation of tail gas and fine powder. The separated fine powder enters the deposition fluidized bed 2 again through the pipeline, and the tail gas enters the tail gas treatment device through the outlet of the cyclone separation device 4. After the reaction is completed, the TiNCl powder synthesized in the deposition fluidized bed 2 enters the powder collection device 3 through the pipeline and the material valve to obtain the target powder. The target powder is then separated from the capture agent and TiNCl powder through a separation process, and the capture agent returns to the capture agent feeding device 1 for reuse, and the TiNCl powder is used as a product.

[0036] Example 3

[0037] In this embodiment, based on the above-mentioned embodiment 2, SiO2 powder with an average particle size of about 30 μm is selected as the capture agent, the reaction temperature of the sedimentation fluidized bed 2 is 420°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 5 is 350°C, the powder collecting device obtains the coated powder, and TiNCl powder is obtained after self-grinding and screening. Figure 2 is the XRD pattern of the obtained TiNCl powder. It can be seen from the figure that the powder is a single-phase TiNCl powder, and the element composition analysis is Ti / N / Cl≈1 / 0.99 / 1.01.

[0038] Example 4

[0039] In this embodiment, based on the above-mentioned embodiment 2, NaCl powder with an average particle size of about 60 μm is selected as the capture agent, the reaction temperature of the sedimentation fluidized bed 2 is 500°C, the inert gas is nitrogen, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1.8, the synthesis time is 60 minutes, the temperature of the insulation pipe 5 is 400°C, the powder collecting device obtains the coated powder, and TiNCl powder is obtained after washing and filtration. Figure 3 The SEM image of the obtained TiNCl powder shows that a hollow powder assembled from TiNCl sheets is obtained, and the maximum lateral dimension of a single sheet is about 10 μm.

[0040] Example 5

[0041] In this embodiment, based on the above-mentioned embodiment 2, Al2O3 powder with an average particle size of about 30 μm, TiN powder with an average particle size of 40 μm, and KCl mixture with an average particle size of 10 μm are selected as capture agents. The reaction temperature of the sedimentation fluidized bed 2 is 450°C, the inert gas is helium, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1.4, the synthesis time is 60 minutes, the temperature of the insulation pipe 5 is 480°C, and the powder collecting device obtains the coated powder. After self-grinding and water washing and filtration in a ball mill, or centrifugal separation, 10 g of TiNCl powder is obtained, and the average particle size of the powder is about 1.2 μm.

[0042] Example 6

[0043] In this embodiment, based on the above-mentioned embodiment 2, CaCl2 powder with an average particle size of about 100 μm, LiCl powder with an average particle size of 20 μm, and KCl mixture with an average particle size of 35 μm are selected as capture agents, the reaction temperature of the sedimentation fluidized bed 2 is 480°C, the inert gas is a mixture of argon and nitrogen, the molar ratio of the nitrogen source gas titanium tetrachloride to the nitrogen source gas ammonia is 1.6, the synthesis time is 120 minutes, the temperature of the insulation pipe 5 is 410°C, the powder collecting device obtains coated powder, and after water washing, filtration and centrifugal separation, TiNCl powder with an average particle size of about 10 μm is obtained.

[0044] 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.

[0045] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0046] 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 TiNCl 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 in a fluidized state at 400-530° C. and grows them into TiNCl powders. Subsequently, the capture agent and TiNCl powders are separated through a separation process.

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

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

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 separation process includes self-grinding screening or solution washing filtration or centrifugal separation.

6. A system for fluidizing and synthesizing TiNCl powder, characterized in that: The system comprises: A capture agent feeding device (1), a sedimentation fluidized bed (2), a powder collecting device (3), a cyclone separation device (4) and a heat-insulating pipeline (5); The discharge port of the capture agent feeding device (1) is connected to the feed port of the sedimentation fluidized bed (2) through a pipeline and a material valve, the bottom feed port of the sedimentation 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 discharge port of the sedimentation fluidized bed (2) is connected to the feed port of the powder collection device (3) through a pipeline and a material valve, the air outlet of the sedimentation fluidized bed (2) is connected to the air inlet of the cyclone separation device (4) through an insulation pipeline (5), the discharge port of the cyclone separation device (4) is connected to the feed port of the sedimentation fluidized bed (2) through a pipeline, and the air outlet of the cyclone separation device (4) is connected to the exhaust gas treatment device.

7. The system for fluidized synthesis of TiNCl powder according to claim 6, characterized in that: The temperature of the heat-insulating pipe (5) is controlled to be greater than or equal to 300°C.

8. The system for fluidized synthesis of TiNCl powder 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 for fluidized synthesis of TiNCl powder according to claim 6, characterized in that: The temperature of the sedimentation fluidized bed is controlled to be 400-530°C.

10. The system for fluidized synthesis of TiNCl powder according to claim 6, characterized in that: The tail gas and part of the fine powder generated by the sedimentation fluidized bed (2) are used in the cyclone separation device (4) to achieve secondary synthesis of TiNCl.

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