Device and method for preparing titanium oxides and vanadium oxides with different valence states through gas phase reduction and multi-stage precipitation

Abstract

The invention discloses a device and a method for preparing titanium oxides and vanadium oxides with different valence states through gas phase reduction and multi-stage precipitation, V2O5 or TiO2 is used as a raw material, proper reaction temperature and atmosphere can be selected according to the requirements of reaction products, and then VxO2x-1 (TiyO2y-1) powder with different valence states is generated; a sample can enter / exit the constant-temperature reaction area in the furnace through the displacement mechanism, the reaction starting time and the reaction ending time are more accurate, and the sample is prevented from reacting in advance in the heating process; by changing the number of collection targets in a product collection system, the collection targets are arranged in a graded manner according to pore size distribution, the gas retention time and the product powder collection area are increased, and finally the product yield is increased. By adjusting the reaction temperature, the reaction atmosphere and the product recovery condition parameters, the kinetic reaction conditions of the gas-solid phase reaction can be obviously improved, and the superfine powder with high purity and low impurity content is finally prepared.

Description

Technical Field

[0001] This invention relates to the field of ultrafine powder synthesis and preparation technology, specifically to an apparatus and method for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation. Background Technology

[0002] Magneli phase is a collective term for a series of non-stoichiometric compounds. They possess excellent oxidation resistance and good resistance to electrochemical corrosion, as well as advantages such as non-magnetism, high electrical conductivity, and unique optical properties. They are widely used in coatings, catalysts, lithium-ion batteries, lead-acid batteries, fuel cells, and flow batteries. Magneli phase titanium oxides include a series of titanium oxides such as Ti2O3, Ti3O5, Ti4O7, Ti5O9, and Ti6O. 11 etc., the general formula is Ti y O 2y-1 The Magneli phase vanadium oxides include a series of vanadium oxides such as V4O7, V5O9, and V6O. 11 V7O 13 Etc., the general formula is V x O 2x-1 Currently, there is limited research on the preparation of these compounds. Zhang Xiaoyan et al. successfully prepared high-density Ti4O7 ceramic electrodes using spark plasma sintering technology; Zhou Debi et al. used TiO2 as a raw material and ammonia decomposition atmosphere as a reducing agent, reacting at 1100 ℃ for 3 h to finally prepare a Ti4O7 phase with high electrical conductivity; Zheng Shili et al. used ethylene glycol as a reducing agent and NH4VO3 as a reactant to prepare nanoscale V4O7 through hydrothermal reduction reaction. In addition to the above methods, other preparation methods include: carbothermic reduction, hydrogen reduction, film formation, and sputtering deposition. However, all of these methods have drawbacks: the carbon / H2 reduction method has a simple process but high energy consumption and poor physicochemical properties of the product; the film formation method requires NH3 and O2 to provide a reducing atmosphere, which places high demands on equipment and makes mass production difficult; the sputtering method makes it difficult to achieve precise control of the product composition, and the product is mostly a multiphase mixture. Summary of the Invention

[0003] The purpose of this invention is to provide an apparatus and method for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation. By adjusting the reaction temperature, reaction atmosphere, and sample recovery regime, high-purity vanadium oxides with low impurity content can be finally prepared. x O 2x-1 (Ti) y O 2y-1 Powders are used to address the shortcomings of existing technologies.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] An apparatus for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation includes a horizontal tube furnace and an alumina ceramic high-temperature reactor tube. The alumina ceramic high-temperature reactor tube is horizontally inserted into the horizontal tube furnace via a bottom support, and the horizontal tube furnace is connected to an external furnace temperature controller via wires. Both ends of the alumina ceramic high-temperature reactor tube are sealed together with stainless steel flanges, with a stainless steel tee connected to the left end and a stainless steel four-way connector connected to the right end. The inlet of the stainless steel tee is connected to a carrier gas supply bottle and a reaction gas mixing tank via pipelines. The lower end of the stainless steel four-way connector is connected to a tail gas absorption and treatment box via a pipeline, and the upper end is connected to a vacuum pump via a pipeline, with a vacuum level display instrument installed on the connecting pipeline of the vacuum pump. The interior of the alumina ceramic high-temperature reactor tube contains stainless steel conduits and a nickel-chromium-nickel-silicon alloy. A temperature measuring thermocouple is provided; one end of the stainless steel conduit is connected to the displacement mechanism, and the other end extends through the stainless steel tee to the inside of the alumina ceramic high-temperature reactor tube. A high-temperature placement tray is welded to the end of the stainless steel conduit, and an alumina ceramic reaction boat for holding reactants is placed on the high-temperature placement tray; an alumina ceramic thermocouple protective sleeve is fitted onto the nickel-chromium-nickel-silicon temperature measuring thermocouple. The nickel-chromium-nickel-silicon temperature measuring thermocouple is inserted into the reaction area inside the alumina ceramic high-temperature reactor tube through the alumina ceramic thermocouple protective sleeve along one end of the stainless steel tee. The product collection end inside the alumina ceramic high-temperature reactor tube is provided with a corresponding alumina ceramic orifice product collection target. A flowing water cooling structure is provided outside the alumina ceramic high-temperature reactor tube. The water cooling structure is wrapped around the outside of the alumina ceramic orifice product collection target. It includes a water cooling cavity. The inlet of the water cooling cavity is connected to the circulating water inlet pipe, and the outlet of the water cooling cavity is connected to the circulating water outlet pipe.

[0006] Furthermore, the stainless steel flanges are fastened together by bolts and nuts, and an O-ring seal is used between the two flanges.

[0007] Furthermore, the displacement mechanism adopts a small 12V / 24V DC electric actuator, which is fixed on a stainless steel tee. Its telescopic end is fixedly connected to a vertical connecting rod, and the other end of the connecting rod is welded to a stainless steel conduit.

[0008] Furthermore, the alumina ceramic reaction boat containing the reactants is located in the isothermal zone of the alumina ceramic high-temperature reaction furnace tube, and the horizontal length of the isothermal zone is greater than the horizontal length of the alumina ceramic reaction boat.

[0009] Furthermore, the connecting pipelines of the carrier gas supply bottle, the reaction gas mixing tank, the vacuum pump, and the tail gas absorption and treatment box are all equipped with corresponding gas shut-off valves.

[0010] Furthermore, the carrier gas supply bottle is used to store Ar gas, and the reaction gas mixing tank is used to store a mixture of H2, CO, and CO2. The inlet end of the reaction gas mixing tank is connected to an H2 supply bottle, a CO supply bottle, and a CO2 supply bottle.

[0011] This invention provides another technical solution: a method for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation, comprising the following steps:

[0012] S1: Place the alumina ceramic high-temperature reaction furnace tube horizontally in the horizontal tube furnace, and install the alumina ceramic porous product collection target, vacuum control system and tail gas treatment system in sequence. Connect the nickel-chromium-nickel-silicon thermocouple to the thermometer to measure the temperature of the constant temperature reaction zone in the furnace in real time.

[0013] S2: Spread a layer of TiO2 or V2O5 powder on the bottom of the alumina ceramic reaction boat, and place the alumina ceramic reaction boat on a high-temperature tray fixed on a stainless steel conduit. Install the stainless steel flange, O-ring, bolts and nuts, stainless steel tee, stainless steel cross, and displacement mechanism in sequence. After fixing the displacement mechanism to the stainless steel conduit, seal the reaction system.

[0014] S3: Turn on the vacuum pump to evacuate the reaction system. If the vacuum gauge reading remains unchanged for a period of time, it proves that the reaction system is well sealed. Through three consecutive steps of "evacuating and venting - filling with reaction gas", the air inside the system is fully exhausted.

[0015] S4: Open the carrier gas inlet and exhaust gas outlet, and maintain ventilation for 60-120 minutes; after ventilation is completed, close all inlets and outlets, turn on the horizontal tube furnace switch and furnace temperature controller, adjust the target temperature to 1000-1200℃, and the heating rate to 5-10℃ / min; after reaching the target temperature, open all inlet and outlet switches, and introduce a certain proportion of CO / CO2 / H2 mixed gas as the reaction gas and Ar as the carrier gas, with a ventilation time of 60-120 minutes;

[0016] S5: After the reaction temperature reaches the target temperature and stabilizes, turn on the displacement mechanism switch. Under the action of the motor, the electric push rod drives the stainless steel tube to move horizontally through the connecting rod until the alumina ceramic reaction boat containing the sample enters the constant temperature zone of the horizontal tube furnace, which is counted as the start of the reaction.

[0017] S6: After sublimation, TiO2 or V2O5 suspended particles undergo a reduction reaction in the constant temperature zone of a horizontal tube furnace to generate ultrafine powder V. x O 2x-1 or Ti y O 2y-1Increase the flow rate of the carrier gas, and the sublimated suspended particles are transported to the alumina ceramic porous product collection target for collection through the carrier gas, while the exhaust gas is recycled and treated through the exhaust gas absorption and treatment box at the outlet end.

[0018] S7: After the reaction is complete, turn off the power to the horizontal tube furnace and allow the reaction system to cool down. After cooling down, first turn off the reaction gas switch, keep the carrier gas continuously flowing in, and after the system temperature drops to room temperature, turn off the carrier gas switch and finally cut off the main power supply. The collected ultrafine powder is transferred to a dry sample bottle through the alumina ceramic pore product collection target and labeled for archiving. The adhering substances on the alumina ceramic pore product collection target are collected with a scraper and combined with the corresponding sample. The inner wall of the reaction tube is rinsed with alcohol and then dried for later use.

[0019] Furthermore, the reaction conditions are controlled by mixed gases of different proportions of CO / CO2 and H2 / CO2 at a fixed temperature, wherein the reaction formula for the CO / CO2 mixed gas is:

[0020] 2CO + O2 = 2CO2

[0021]

[0022]

[0023] In the formula, The standard Gibbs free energy of formation for the reaction; R is the partial pressure of oxygen in the reaction system; R is the gas constant; T is the reaction temperature. This represents the partial pressure ratio of CO to CO2 in the gas mixture.

[0024] Furthermore, the alumina ceramic porous product collection target used to collect the reaction products is a porous alumina ceramic collection target. The cooling rate of the reaction products can be controlled by adjusting the number, position and arrangement of the collection targets, thereby controlling the morphology of the reaction products. If the product particle size is small, filter paper with a smaller particle size can be selected to be used in combination with the collection target to improve the product recovery rate.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The apparatus and method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation of the present invention can significantly improve the solid-phase reaction interface, make the gas-solid phase reaction more complete, and improve the reaction efficiency compared with conventional high-temperature reactors.

[0027] 2. The apparatus and method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation of the present invention utilizes a carrier gas to transport the reaction products to a water-cooled chamber for cooling, and then recovers them through a multi-layer collection target. Compared with conventional reaction equipment sample recovery devices, the present invention can extend the gas residence time and product cooling rate by adjusting the position and number of collection targets, thereby achieving the purpose of controlling the type, particle size and morphology of the reaction products.

[0028] 3. The apparatus and method of the present invention for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation. The sample is moved in and out of the constant temperature zone of the horizontal reactor by the movement of an electric push rod, thereby achieving the purpose of starting / ending the reaction. By controlling the start / end time of the reaction, the disadvantage of the conventional high-temperature reaction equipment, where the sample reacts before reaching the formal reaction temperature, can be avoided, which ultimately affects the purity of the product.

[0029] 4. The apparatus and method of the present invention for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation are obtained by controlling the mixing of reaction gases at different temperatures, flow rates, and volume ratios. Compared with conventional high-temperature reaction equipment, this apparatus can prepare ultrafine vanadium oxides with different phase structures under different temperature and atmospheric conditions. x O 2x-1 (Ti) y O 2y-1 Powders, such as Ti3O5, Ti4O7, V4O7, V5O9, etc. Attached Figure Description

[0030] Figure 1 This is an overall structural diagram of the preparation device of the present invention;

[0031] Figure 2 This is a schematic diagram of the pore size of the alumina ceramic porous product collection target of the present invention.

[0032] Figure 3 This is a schematic diagram of the water-cooling structure of the present invention;

[0033] Figure 4 This is a schematic diagram of the displacement mechanism of the present invention.

[0034] In the diagram: 1. Carrier gas supply bottle; 2. H2 supply bottle; 3. CO supply bottle; 4. CO2 supply bottle; 5. Reactant gas mixing tank; 6. Displacement mechanism; 7. Connecting rod; 8. Gas shut-off valve; 9. O-ring; 10. Bolt and nut; 11. Stainless steel flange; 13. Furnace temperature controller; 14. Horizontal tube furnace; 15. Stainless steel conduit; 16. High-temperature storage tray; 17. Alumina ceramic reaction boat; 18. Alumina ceramic high-temperature reaction furnace tube; 19. Water-cooled cavity; 20. Circulating water inlet pipe; 21. Circulating water outlet pipe; 22. Alumina ceramic porous product collection target; 25. Vacuum degree display instrument; 26. Vacuum pump; 27. Stainless steel tee; 28. Stainless steel cross; 29. ​​Alumina ceramic thermocouple protection sleeve; 30. Nickel-chromium / nickel-silicon thermocouple; 31. Tail gas absorption and treatment box; 32. Support frame. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see Figure 1-4This invention provides an apparatus for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation, comprising a horizontal tube furnace 14 and an alumina ceramic high-temperature reactor tube 18; the alumina ceramic high-temperature reactor tube 18 is horizontally inserted into the horizontal tube furnace 14 via a bottom support 32, and the horizontal tube furnace 14 is connected to an external furnace temperature controller 13 via wires; the two ends of the alumina ceramic high-temperature reactor tube 18 are sealed together by stainless steel flanges 11, with a stainless steel tee 27 connected to the left end of the stainless steel flange 11 and a stainless steel cross 28 connected to the right end of the stainless steel flange 11. To ensure the reaction system is fully isolated from the external environment, the stainless steel flanges 11 are fastened with bolts and nuts 10, and an O-ring 9 is used to seal between the two flanges. The inlet of the stainless steel tee 27 is connected to a carrier gas supply bottle 1 and a reaction gas mixing tank 5 via pipelines. The lower port of the stainless steel four-way valve 28 is connected to a tail gas absorption and treatment box 31 via a pipeline, and the upper port is connected to a vacuum pump 26 via a pipeline. A vacuum level display instrument 25 is installed on the connecting pipeline of the vacuum pump 26. The interior of the alumina ceramic high-temperature reactor tube 18 is equipped with a stainless steel conduit 15 and a nickel-chromium-nickel-silicon measuring instrument. A thermocouple 30 is included; one end of the stainless steel conduit 15 is connected to the displacement mechanism 6, and the other end extends through the stainless steel tee 27 into the interior of the alumina ceramic high-temperature reactor tube 18. A high-temperature tray 16 is welded to the end of the stainless steel conduit 15, and an alumina ceramic reaction boat 17 for holding reactants is placed on the high-temperature tray 16; wherein, the displacement mechanism 6 adopts a small 12V / 24V DC electric actuator, which is fixed to the stainless steel tee 27, and its telescopic end is fixedly connected to a vertical connecting rod 7, the other end of which is welded to the stainless steel conduit 15; the alumina ceramic reaction boat 17 containing reactants... The constant temperature zone is located in the alumina ceramic high-temperature reactor tube 18, and the length of the constant temperature zone in the horizontal direction is greater than the length of the alumina ceramic reaction boat 17 in the horizontal direction; the nickel-chromium-nickel-silicon thermocouple 30 is fixed and protected by an alumina ceramic thermocouple protective sleeve 29. The nickel-chromium-nickel-silicon thermocouple 30 is inserted into the reaction zone inside the alumina ceramic high-temperature reactor tube 18 through the alumina ceramic thermocouple protective sleeve 29 along one end of the stainless steel four-way connector 28. The depth to which the alumina ceramic thermocouple protective sleeve 29 is inserted into the reactor tube through the stainless steel flange 11 is equivalent to the position of the reactants.The alumina ceramic high-temperature reactor tube 18 has a corresponding alumina ceramic porous product collection target 22 at its internal product collection end. A flowing water-cooling structure surrounds the alumina ceramic porous product collection target 22 and includes a water-cooling chamber 19. The inlet of the water-cooling chamber 19 is connected to a circulating water inlet pipe 20, and the outlet of the water-cooling chamber 19 is connected to a circulating water outlet pipe 21. When flowing cold water passes through the water-cooling chamber 19, it ensures that the temperature in this area remains below 50 ℃. When the reaction product arrives in this area with the carrier gas, it can cool the sample to room temperature in a short time, preventing the sample from undergoing another chemical reaction and ultimately affecting the product purity.

[0037] In the above embodiments, the connecting pipelines of the carrier gas supply bottle 1, the reaction gas mixing tank 5, the vacuum pump 26, and the tail gas absorption and treatment box 31 are all equipped with corresponding gas shut-off valves 8. The carrier gas supply bottle 1 is used to store Ar gas, and the reaction gas mixing tank 5 is used to store a mixture of H2, CO, and CO2. The inlet end of the reaction gas mixing tank 5 is connected to the H2 supply bottle 2, the CO supply bottle 3, and the CO2 supply bottle 4. In practical operation, the main reaction site is a horizontal tube furnace 14. The central part of the horizontal tube furnace 14 is an alumina ceramic high-temperature reactor tube 18. The two ends of the alumina ceramic high-temperature reactor tube 18 are connected to stainless steel tees 27 and stainless steel crosses 28, respectively, for connection to the reaction gas, carrier gas, and reaction exhaust gas. Inside the alumina ceramic high-temperature reactor tube 18, an alumina ceramic reaction boat 17 is installed to hold the reaction raw materials. A nickel-chromium / nickel-silicon thermocouple 30 is directly inserted into the reaction zone to measure the actual temperature of the constant-temperature reaction zone in real time. A stainless steel conduit 15 is connected to an electric push rod installed on the stainless steel tees 27. The connecting rod 7 on the electric push rod drives the stainless steel conduit 15 to move, realizing the reaction... The sample enters and exits the isothermal zone of the horizontal tube furnace 14, thereby achieving the purpose of starting and ending the reaction; one end of the stainless steel tee 27 is the reaction gas inlet, and the other end is the carrier gas inlet; the lower end of the stainless steel four-way 28 is set as the gas outlet, connected to the tail gas absorption and treatment box 31, and the upper end is connected to the rotary vane vacuum pump 26 equipped with a vacuum degree display instrument 25; by changing different reaction gas volume ratios, the purpose of preparing different pure phases of V4O7, V5O9, Ti4O7, and Ti5O9 can be achieved; by changing the number and distribution of alumina ceramic porous product collection targets 22, the collection area and cooling rate of reaction product particles can be significantly improved, thereby obtaining ultrafine V4O7 particles with different particle sizes and morphologies. x O 2x-1 (Ti) y O 2y-1The product is a phase powder; the position, number and arrangement of the alumina ceramic porous product collection target 22 can be adjusted according to the reaction requirements; when collecting reaction products with fine particle size, filter paper with a pore size of 0.05-0.5 μm can be attached to the surface of the collection target; the reaction products are cooled, attached and recovered in this area along with the carrier gas.

[0038] To further illustrate the present invention, based on the above-described apparatus, a method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation is also provided, comprising the following steps:

[0039] S1: Place the alumina ceramic high-temperature reaction furnace tube 18 horizontally in the horizontal tube furnace 14, and install the alumina ceramic porous product collection target 22, vacuum control system and tail gas treatment system in sequence. Connect the nickel-chromium-nickel-silicon thermocouple 30 to the thermometer to measure the temperature of the constant temperature reaction zone in the furnace in real time.

[0040] S2: Spread a layer of TiO2 or V2O5 powder on the bottom of the alumina ceramic reaction boat 17, and place the alumina ceramic reaction boat 17 on the high-temperature placement tray 16 fixed on the stainless steel conduit 15. Install the stainless steel flange 11, O-ring 9, bolts and nuts 10, stainless steel tee 27, stainless steel cross 28, and displacement mechanism 6 in sequence. After fixing the displacement mechanism 6 to the stainless steel conduit 15, seal the reaction system.

[0041] S3: Turn on the vacuum pump 26 to evacuate the reaction system. If the vacuum gauge reading remains unchanged for a period of time, it proves that the reaction system is well sealed. Through three consecutive steps of "evacuating and venting - filling with reaction gas", the air inside the system is fully exhausted.

[0042] S4: Open the carrier gas inlet and exhaust gas outlet, and maintain ventilation for 60-120 minutes; after ventilation is completed, close all inlets and outlets, turn on the horizontal tube furnace 14 switch and furnace temperature controller 13, adjust the target temperature to 1000-1200℃, and the heating rate to 5-10℃ / min; after reaching the target temperature, open all inlet and outlet switches, and introduce a certain proportion of CO / CO2 / H2 mixed gas as the reaction gas and Ar as the carrier gas, with a ventilation time of 60-120 minutes;

[0043] S5: After the reaction temperature reaches the target temperature and stabilizes, turn on the displacement mechanism 6 switch. Under the action of the motor, the electric push rod drives the stainless steel tube 15 to move horizontally through the connecting rod 7, so that the alumina ceramic reaction boat 17 containing the sample enters the constant temperature zone of the horizontal tube furnace 14, which is marked as the start of the reaction.

[0044] S6: After sublimation, TiO2 or V2O5 suspended particles undergo a reduction reaction in the constant temperature zone 14 of a horizontal tube furnace to generate ultrafine powder V. x O 2x-1 or Ti y O 2y-1 Increase the flow rate of the carrier gas, and the sublimated suspended particles are transported to the alumina ceramic porous product collection target 22 for collection through the carrier gas, while the exhaust gas is recycled and treated through the exhaust gas absorption and treatment box 31 at the outlet end.

[0045] S7: After the reaction is complete, turn off the power to the horizontal tube furnace 14 and allow the reaction system to cool down. After cooling down, first turn off the reaction gas switch, keep the carrier gas continuously flowing in, and after the system temperature drops to room temperature, turn off the carrier gas switch and finally cut off the main power supply. The collected ultrafine powder is transferred to a dry sample bottle through the alumina ceramic porous product collection target 22 and labeled for archiving. The adhering substances on the alumina ceramic porous product collection target 22 are collected with a scraper and combined with the corresponding sample. The inner wall of the reaction tube is rinsed with alcohol and then dried for later use.

[0046] In the above method, the reactants are usually V₂O₅ and TiO₂, placed in a porcelain boat, which can be moved horizontally by an electric push rod and connecting rod 7. The start / end of the reaction is achieved by controlling the leaching of the reactants into the constant temperature zone of the horizontal tube furnace 14. The reaction gas is usually a mixture of two or three of CO / CO₂ / H₂, with a total gas flow rate of 200-500 sccm. The carrier gas is usually a high-purity inert gas N₂ or Ar. The role of the carrier gas is to transport the reaction products to the water-cooled area for cooling and recovery, and its flow rate is usually 2-3 times that of the reaction mixture, i.e., 600-1000 sccm. The reaction conditions are controlled by different proportions of CO / CO₂, H₂ / CO₂, etc., at a fixed temperature. Taking CO / CO₂ mixture as an example, the reaction formula is:

[0047] 2CO + O2 = 2CO2

[0048]

[0049]

[0050] In the formula The standard Gibbs free energy of formation for the reaction; R is the partial pressure of oxygen in the reaction system; R is the gas constant; T is the reaction temperature. This represents the partial pressure ratio of CO to CO2 in the gas mixture.

[0051] In the above method, the alumina ceramic porous product collection target 22 used to collect the reaction products is a porous alumina ceramic collection target. The cooling rate of the reaction products can be controlled by adjusting the number, position and arrangement of the collection targets, thereby achieving the purpose of controlling the morphology of the reaction products. In particular, if the product particle size is small, filter paper with a smaller particle size can be selected to be used in combination with the collection target, thereby achieving the purpose of improving the product recovery rate.

[0052] To further explain and illustrate the above embodiments, the present invention provides the following specific examples:

[0053] Example 1: Taking the preparation of pure phase V4O7 as an example, the implementation steps of this method are as follows:

[0054] Step 1: Place the alumina ceramic high-temperature reactor tube 18 horizontally into the horizontal tube furnace 14. Install stainless steel tees 27, stainless steel crosses 28 and stainless steel flanges 11 on both sides of the alumina ceramic high-temperature reactor tube 18 respectively. Use O-rings 9, bolts and nuts 10 to achieve a tight seal.

[0055] Step 2: After placing 5-10 g of V2O3 sample into the alumina ceramic reaction boat 17, place it on the high-temperature tray 16 and connect it to the stainless steel conduit 15; before the reaction starts, the sample is at the cold end of the alumina ceramic high-temperature reaction furnace tube 18 to prevent the sample from participating in the reaction in advance and thus affecting the purity of the product; insert a nickel-chromium-nickel-silicon thermocouple 30 with an external alumina ceramic thermocouple protective sleeve 29 into the gas outlet end, with the top of the nickel-chromium-nickel-silicon thermocouple 30 aligned with the constant temperature zone.

[0056] Step 3: Turn on the vacuum pump 26 to evacuate the reaction system. When the vacuum indicator 25 reads -0.1 MPa and remains unchanged for about 30 minutes, it indicates that the vacuum of the reaction system is good. Then, fill the reaction system with inert gas and restore it to normal pressure. Repeat the above steps 3 times to remove as much residual air as possible from the reaction system. Turn on the reaction gas switch, adjust the H2 flow rate to 200 sccm and the CO2 flow rate to 4 sccm, and ventilate for 2 hours.

[0057] Step 4: Turn on the horizontal tube furnace 14 switch, set the target temperature to 1200 ℃, and control the heating rate at 4-8 ℃ / min; when the temperature of the constant temperature zone measured by the nickel-chromium-nickel-silicon thermocouple 30 reaches 1200 ℃ and stabilizes, turn on the electric push rod switch, set the moving distance, and transport the alumina ceramic reaction boat 17 carrying the sample to the constant temperature zone area. This marks the start of the reaction.

[0058] Step 5: After the reaction begins, turn on the switch of Ar support gas supply bottle 1. The gas flow rate is 400 scm. The V4O7 particles generated by the reaction are transported to the alumina ceramic porous product collection target 22 at a lower temperature for sample recovery under the action of the support gas. The reaction tail gas is absorbed and treated by the tail gas absorption and treatment box 31.

[0059] Step 6: After the reaction is complete, turn off the power to the horizontal tube furnace 14; after the reaction system temperature drops to room temperature, first turn off the reaction gas switch, pass the carrier gas for 30 minutes to fully exhaust the reaction gas in the furnace, then turn off all switches, open the stainless steel flanges 11 on both sides of the alumina ceramic high-temperature reaction furnace tube 18, take out the alumina ceramic porous product collection target 22, and finally obtain the reaction product V4O7.

[0060] Example 2: Taking the preparation of pure phase Ti4O7 as an example, the implementation steps of this method are as follows:

[0061] Step 1: Place the alumina ceramic high-temperature reactor tube 18 horizontally into the horizontal tube furnace 14. Install stainless steel tees 27, stainless steel crosses 28 and stainless steel flanges 11 on both sides of the alumina ceramic high-temperature reactor tube 18 respectively. Use O-rings 9, bolts and nuts 10 to achieve a tight seal.

[0062] Step 2: After placing 5-10 g of TiO2 sample into the alumina ceramic reaction boat 17, place it on the high-temperature tray 16 and connect it to the stainless steel conduit 15; before the reaction starts, the sample is at the cold end of the alumina ceramic high-temperature reaction furnace tube 18 to prevent the sample from participating in the reaction in advance and thus affecting the purity of the product; a nickel-chromium-nickel-silicon thermocouple 30 with an external alumina ceramic thermocouple protective sleeve 29 is placed at the gas outlet end, with the top of the nickel-chromium-nickel-silicon thermocouple 30 aligned with the constant temperature zone.

[0063] Step 3: Turn on the vacuum pump 26 to evacuate the reaction system. When the vacuum indicator 25 reads -0.1 MPa and remains unchanged for about 30 minutes, it indicates that the vacuum of the reaction system is good. Then, fill the reaction system with inert gas and restore it to normal pressure. Repeat the above steps 3 times to remove as much residual air as possible from the reaction system. Turn on the reaction gas switch, adjust the CO flow rate to 180 sccm and the CO2 flow rate to 18 sccm, and ventilate for 2 hours.

[0064] Step 4: Turn on the horizontal tube furnace 14 switch, set the target temperature to 1200 ℃, and control the heating rate at 4-8 ℃ / min; when the temperature of the constant temperature zone measured by the nickel-chromium-nickel-silicon thermocouple 30 reaches 1100 ℃ and stabilizes, turn on the electric push rod switch, set the moving distance, and transport the alumina ceramic reaction boat 17 carrying the sample to the constant temperature zone area. This is the start of the reaction.

[0065] Step 5: After the reaction begins, turn on the switch of Ar support gas supply bottle 1. The gas flow rate is 400 scm. The Ti4O7 particles generated by the reaction are transported to the alumina ceramic porous product collection target 22 at a lower temperature for sample recovery under the action of the support gas. The reaction tail gas is absorbed and treated by the tail gas absorption and treatment box 31.

[0066] Step 6: After the reaction is complete, turn off the power to the horizontal tube furnace 14; after the reaction system temperature drops to room temperature, first turn off the reaction gas switch, pass the carrier gas for 30 minutes to fully exhaust the reaction gas in the furnace, then turn off all switches, open the stainless steel flanges 11 on both sides of the alumina ceramic high-temperature reaction furnace tube 18, take out the alumina ceramic porous product collection target 22, and finally obtain the reaction product Ti4O7.

[0067] In summary, this invention provides an apparatus and method for preparing titanium oxides and vanadium oxides of different valence states through gas-phase reduction and multi-stage precipitation. Using V₂O₅ (TiO₂) as raw material, the method of "high-temperature gas-phase reduction + multi-stage precipitation" recovers V₂ oxides of different valence states. x O 2x-1 (Ti) y O 2y-1 (Powder). Specifically, it includes an atmosphere control system, sample transport system, temperature control and measurement system, gas inlet and outlet system, reduction reaction system, product collection system, and exhaust gas treatment system. It can select appropriate reaction temperature and atmosphere according to the requirements of the reaction products, thereby generating V in different valence states. x O 2x-1 (Ti) y O 2y-1 The powder sample can be conveyed into and out of the constant-temperature reaction zone inside the furnace via a transfer system, allowing for more accurate start and end times of the reaction and preventing premature reaction during heating, which could affect product purity. By changing the number of collection targets in the product collection system and arranging them in a graded manner according to pore size distribution, the gas residence time and product powder collection area are increased, ultimately improving product yield. Compared with conventional high-temperature synthesis equipment, this invention can significantly improve the kinetic reaction conditions of the gas-solid phase reaction. By adjusting the reaction temperature, reaction atmosphere, and product recovery parameters, high-purity V powder with low impurity content can be finally prepared. x O 2x-1 (Ti) y O 2y-1 Powder.

[0068] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation, characterized in that, The system includes a horizontal tube furnace (14) and an alumina ceramic high-temperature reactor tube (18). The alumina ceramic high-temperature reactor tube (18) is horizontally inserted into the horizontal tube furnace (14) via a bottom support (32). The horizontal tube furnace (14) is connected to an external furnace temperature controller (13) via a wire. The two ends of the alumina ceramic high-temperature reactor tube (18) are sealed together by stainless steel flanges (11), with a stainless steel tee (27) connected to the left end of the stainless steel flange (11) and a stainless steel cross (27) connected to the right end of the stainless steel flange (11). 8); The inlet end of the stainless steel tee (27) is connected to a carrier gas supply bottle (1) and a reaction gas mixing tank (5) via pipelines; The lower end of the stainless steel four-way valve (28) is connected to a tail gas absorption and treatment box (31) via pipelines, and the upper end is connected to a vacuum pump (26) via pipelines, and a vacuum degree display instrument (25) is provided on the connecting pipeline of the vacuum pump (26); The interior of the alumina ceramic high-temperature reactor tube (18) is provided with a stainless steel conduit (15) and a nickel-chromium-nickel-silicon thermocouple (30); The stainless steel conduit (15) is connected to a carrier gas supply bottle (1) and a reaction gas mixing tank (5) via pipelines. One end of 5) is connected to the displacement mechanism (6), and the other end extends through the stainless steel tee (27) to the inside of the alumina ceramic high-temperature reactor tube (18), and a high-temperature tray (16) is welded to the end of the stainless steel conduit (15). An alumina ceramic reaction boat (17) for holding reactants is placed on the high-temperature tray (16); an alumina ceramic thermocouple protective sleeve (29) is fitted on the nickel-chromium-nickel-silicon thermocouple (30), and the nickel-chromium-nickel-silicon thermocouple (30) passes through the alumina ceramic thermocouple protective sleeve (29) along the stainless steel tee (27). One end of 8) is inserted into the reaction area inside the alumina ceramic high-temperature reactor tube (18). The product collection end inside the alumina ceramic high-temperature reactor tube (18) is provided with a corresponding alumina ceramic hole product collection target (22). The alumina ceramic high-temperature reactor tube (18) is provided with a flowing water cooling structure. The water cooling structure is wrapped around the outside of the alumina ceramic hole product collection target (22). It includes a water cooling cavity (19). The inlet of the water cooling cavity (19) is connected to the circulating water inlet pipe (20), and the outlet of the water cooling cavity (19) is connected to the circulating water outlet pipe (21).

2. The apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: The stainless steel flanges (11) are fastened together by bolts and nuts (10), and an O-ring (9) is used to seal between the two flanges.

3. The apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: The displacement mechanism (6) uses a small DC electric push rod of 12V / 24V. The electric push rod is fixed on a stainless steel tee (27), and its telescopic end is fixedly connected to a vertical connecting rod (7). The other end of the connecting rod (7) is welded to a stainless steel conduit (15).

4. The apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: The alumina ceramic reaction boat (17) containing the reactants is located in the constant temperature zone of the alumina ceramic high-temperature reaction furnace tube (18), and the length of the constant temperature zone in the horizontal direction is greater than the length of the alumina ceramic reaction boat (17) in the horizontal direction.

5. The apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: The connecting pipelines of the carrier gas supply bottle (1), the reaction gas mixing tank (5), the vacuum pump (26), and the tail gas absorption and treatment box (31) are all equipped with corresponding gas shut-off valves (8).

6. The apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: The carrier gas supply bottle (1) is used to store Ar gas, and the reaction gas mixing tank (5) is used to store H2, CO and CO2 mixed gas. The inlet end of the reaction gas mixing tank (5) is connected to the H2 supply bottle (2), CO supply bottle (3) and CO2 supply bottle (4).

7. A method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation, implemented based on the apparatus for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 1, characterized in that: Includes the following steps: S1: Place the alumina ceramic high-temperature reaction furnace tube (18) horizontally in the horizontal tube furnace (14), install the alumina ceramic porous product collection target (22), vacuum control system and tail gas treatment system in sequence, and connect the nickel-chromium-nickel-silicon thermocouple (30) to the thermometer to measure the temperature of the constant temperature reaction zone in the furnace in real time. S2: Spread a layer of TiO2 or V2O5 powder on the bottom of the alumina ceramic reaction boat (17), and place the alumina ceramic reaction boat (17) on the high-temperature placement tray (16) fixed on the stainless steel conduit (15). Install the stainless steel flange (11), O-ring (9), bolts and nuts (10), stainless steel tee (27), stainless steel cross (28), and displacement mechanism (6) in sequence. After fixing the displacement mechanism (6) to the stainless steel conduit (15), seal the reaction system. S3: Turn on the vacuum pump (26) to evacuate the reaction system. If the vacuum gauge reading remains unchanged for a period of time, it proves that the reaction system is well sealed. Through three consecutive "vacuuming and exhausting - filling with reaction gas" steps, the air inside the system is fully exhausted. S4: Open the carrier gas inlet and the tail gas outlet, and keep the gas flowing for 60-120 minutes; after the gas flow is completed, close all the inlets and outlets, turn on the horizontal tube furnace (14) switch and the furnace temperature controller (13), adjust the target temperature to 1000-1200℃, and the heating rate to 5-10℃ / min; after the target temperature is reached, open all the inlet and outlet switches, and introduce a certain proportion of CO / CO2 / H2 mixed gas as the reaction gas and Ar as the carrier gas, and the gas flow time is 60-120 minutes; S5: After the reaction temperature reaches the target temperature and stabilizes, turn on the displacement mechanism (6) switch. Under the action of the motor, the electric push rod drives the stainless steel tube (15) to move horizontally through the connecting rod (7) until the alumina ceramic reaction boat (17) containing the sample enters the constant temperature zone of the horizontal tube furnace (14), which is counted as the start of the reaction. S6: After the sublimated TiO2 or V2O5 suspended particles undergo a reduction reaction in the constant temperature zone of a horizontal tube furnace (14), ultrafine powder V is generated. x O 2x-1 or Ti y O 2y-1 Increase the flow rate of the carrier gas, and the sublimated suspended particles are transported to the alumina ceramic porous product collection target (22) for collection through the carrier gas, while the tail gas is recycled and disposed of through the tail gas absorption and treatment box (31) at the outlet end. S7: After the reaction is completed, turn off the power supply of the horizontal tube furnace (14) and cool down the reaction system. After the cooling is completed, first turn off the switch of the reaction gas, keep the carrier gas continuously flowing in, and after the system temperature drops to room temperature, turn off the carrier gas switch and finally cut off the main power supply. The collected ultrafine powder is transferred to the dry sample bottle through the alumina ceramic pore product collection target (22) and labeled for archiving. The adhering substances on the alumina ceramic pore product collection target (22) are collected with a scraper and combined into the corresponding sample. The inner wall of the reaction tube is rinsed with alcohol and then dried for later use.

8. The method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 7, characterized in that: The reaction conditions are controlled by a mixture of CO / CO2 and H2 / CO2 gases in different proportions at a fixed temperature. The reaction formula for the CO / CO2 mixture is as follows: 2CO + O2 = 2CO2 In the formula, The standard Gibbs free energy of formation for the reaction; R is the partial pressure of oxygen in the reaction system; R is the gas constant; T is the reaction temperature. This represents the partial pressure ratio of CO to CO2 in the gas mixture.

9. The method for preparing titanium oxides and vanadium oxides of different valence states by gas-phase reduction and multi-stage precipitation as described in claim 7, characterized in that: The alumina ceramic porous product collection target (22) used to collect reaction products is a porous alumina ceramic collection target. The cooling rate of the reaction products can be controlled by adjusting the number, position and arrangement of the collection targets, thereby controlling the morphology of the reaction products. If the product particle size is small, filter paper with a smaller particle size can be selected to be used in combination with the collection target to improve the product recovery rate.

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