CN110627122A

CN110627122A - Preparation of VO by solid phase method2Method for phase change materials

Info

Publication number: CN110627122A
Application number: CN201911017691.5A
Authority: CN
Inventors: 刘波; 彭穗; 辛亚男
Original assignee: Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
Current assignee: Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2019-12-31

Abstract

The invention discloses a solid phase method for preparing VO₂A method for preparing a phase-change material belongs to the technical field of vanadium dioxide preparation, and comprises the following steps: will V₂O₅、V₂O₃Mixing with sulfuric acid, and reacting under the protection of argon to obtain VOSO₄Then the VOSO is added₄Decomposing to obtain VO₂. The invention uses V₂O₅And V₂O₃Preparation of VO as starting Material₂The method has the advantages of simple raw materials, low requirement on equipment, simple process flow, low cost and easy industrial production. VO prepared by the invention₂High purity, good crystallinity, low phase transition temperature (lower than 68 ℃), and can be widely applied to the fields of intelligent windows, photoelectric switches, thermistors and the like.

Description

Preparation of VO by solid phase method2Method for phase change materials

Technical Field

The invention belongs to the technical field of vanadium dioxide preparation, and particularly relates to a method for preparing VO by a solid phase method₂A method of phase change materials.

Background

Vanadium dioxide (VO)₂) Is a phase-change material, has the characteristic of changing from a monoclinic semiconductor phase to a tetragonal metal phase at the temperature of 68 ℃, and has the optical property and the electric propertyThe chemical properties are mutated. The material can be widely applied to the fields of intelligent windows, laser radiation resistance, photoelectric switches, antistatic coatings and the like.

At present, VO is prepared₂The method of the material mainly comprises the following steps: hydrothermal method, chemical precipitation method, thermal decomposition method, sol-gel method, vapor deposition method, sputtering method, and the like. Wherein, the sol-gel method, the vapor deposition method and the sputtering method are mainly used for preparing VO₂A film. The hydrothermal method, chemical precipitation method and thermal decomposition method are mainly used for preparing VO₂And (3) powder.

Although the hydrothermal method can directly synthesize VO₂But has the defects of low yield, small yield, high requirements on equipment and environment and the like. For example, CN102616849A discloses a method for directly synthesizing M-phase vanadium dioxide nanoparticles by a liquid phase method: one or a mixture of two of vanadium pentoxide and metavanadate is used as a raw material, a reducing agent is slowly dripped into the raw material, a precursor is obtained through constant-temperature reaction, the precursor is mixed with distilled water and then transferred into a reaction steel kettle with a polytetrafluoroethylene lining, and a bluish-black M-phase vanadium dioxide nano-particle product is obtained through hydrothermal reaction. CN108373171A discloses a method for preparing vanadium dioxide by a hydrothermal method, which comprises the following steps: dissolving vanadyl sulfate powder in water to prepare a solution to be reacted with the vanadium concentration of 10-30 g/L, and reacting the obtained solution to be reacted at the temperature of 180-250 ℃ for 6-15 hours to obtain vanadium dioxide slurry; and carrying out solid-liquid separation and vacuum drying to obtain vanadium dioxide. CN107117654A discloses a method for preparing vanadium dioxide from vanadium-containing solution: putting a catalyst (one of palladium chloride, palladium and platinum) and a vanadium-containing solution into a reaction kettle, reacting for 0.5-4 h under the condition of a hydrogen atmosphere and 100-250 ℃, carrying out solid-liquid separation to obtain a tetravalent vanadium oxide filter cake and filtrate, then carrying out vacuum drying on the tetravalent vanadium oxide filter cake, and calcining for 0.5-2 h under the condition of 300-500 ℃ and an inert atmosphere to obtain vanadium dioxide.

The chemical precipitation method generally can not obtain crystalline products, and heat treatment is needed subsequently, so that the defects of complex process flow, high cost and the like exist. For example, CN102795668A discloses a VO₂The preparation method comprises the following steps: preparing ammonium metavanadate/ammonium vanadate into waterAdding a reducing agent and an accelerant into the solution, wherein the reducing agent comprises glucose, fructose, lactose, formaldehyde, ethylene glycol and the like, the accelerant comprises ammonium carbonate, ammonium chloride, ammonium bicarbonate, ammonium sulfate and the like, reacting at the temperature of 50-100 ℃ to obtain an ammonium trivanadate purple precipitate, putting an ammonium trivanadate precursor into a vacuum or inert gas environment, and preserving heat at the temperature of 400-900 ℃ for 5-300 min to prepare VO₂And (3) powder.

Preparation of VO by thermal decomposition₂The raw materials used by the powder are usually ammonium metavanadate and vanadium pentoxide, the temperature required by thermal decomposition is over 1000 ℃, the energy consumption is very high, and the method is not suitable for industrial production.

Disclosure of Invention

The invention aims to provide a solid phase method for preparing VO, which is beneficial to industrial application₂A method of phase change material comprising the steps of:

will V₂O₅、V₂O₃Mixing with sulfuric acid, and reacting under the protection of argon to obtain VOSO₄Then the VOSO is added₄Decomposing to obtain VO₂。

Wherein, the solid phase method is used for preparing VO₂Method of phase change material, said V₂O₅And V₂O₃The molar ratio of (A) is 1.0-1.2: 1; preferably 1: 1.

wherein, the solid phase method is used for preparing VO₂Method for preparing phase change material, the molar ratio of the sulfuric acid to the total vanadium in the raw material is n (H)₂SO₄): n (TV) 1.2 to 2.0: 1; preferably 1.2: 1.

wherein, the solid phase method is used for preparing VO₂The method of the phase-change material comprises the step of mixing 50-98% of sulfuric acid by mass.

Wherein, the solid phase method is used for preparing VO₂Method for producing a VOSO₄The reaction temperature is 80-200 ℃, and the reaction time is 1-2.5 h; preferably, the generation of VOSO₄The reaction temperature of (2) was 140 ℃.

Wherein, the solid phase method is used for preparing VO₂Method of phase change material, said VOSO₄Has a decomposition temperature ofDecomposing for 3-6 h at 600-700 ℃; preferably, the VOSO₄The decomposition temperature of (A) was 600 ℃.

The invention has the beneficial effects that:

the invention uses V₂O₅And V₂O₃Preparation of VO as starting Material₂The method has the advantages of simple raw materials, low requirement on equipment, simple process flow, low cost and easy industrial production. VO prepared by the invention₂High purity, good crystallinity, low phase transition temperature (lower than 68 ℃), and can be widely applied to the fields of intelligent windows, photoelectric switches, thermistors and the like.

Drawings

FIG. 1 shows M-phase VO obtained in example 2 of the present invention₂Differential thermal profile of the powder;

FIG. 2 shows M-phase VO obtained in example 2 of the present invention₂X-ray diffraction pattern of the powder.

Detailed Description

In particular to a solid phase method for preparing VO₂A method of phase change material comprising the steps of: will V₂O₅、V₂O₃Mixing with sulfuric acid, and reacting under the protection of argon to obtain VOSO₄Then the VOSO is added₄Decomposing to obtain VO₂。

The reactions that occur in the present invention are as follows:

V₂O₅+V₂O₃+4H₂SO₄＝4VOSO₄+4H₂O

2VOSO₄＝2VO₂+2SO₃

since nitrogen reacts with vanadium, the process of the invention can only be carried out under argon protection or in a vacuum atmosphere.

In the method of the present invention, said V₂O₅And V₂O₃Too high or too low of the molar ratio of (A) can cause vanadium oxide inclusion in the product and influence VO₂Phase change performance. Therefore, the invention will V₂O₅And V₂O₃The molar ratio of (A) to (B) is set to 1.0-1.2: 1; preferably 1: 1.

in the method of the invention, if the dosage of the sulfuric acid is too low, the reaction is not completely carried out; if the dosage of the sulfuric acid is too high, the energy consumption is increased, and the method has no practical significance. Thus, the present invention sets the molar ratio of sulfuric acid to total vanadium in the feedstock to n (H)₂SO₄): n (TV) 1.2 to 2.0: 1; preferably 1.2: 1.

in the process of the invention, VOSO is generated₄Temperature and decomposition of VOSO₄If the temperature of (a) is too low, the reaction cannot occur, and if the temperature is too high, the energy consumption is increased, which is of no practical significance. Therefore, the present invention will generate VOSO₄The reaction temperature is set to be 80-200 ℃, and the reaction time is 1-2.5 h; preferably, the generation of VOSO₄The reaction temperature of (2) is 140 ℃; VOSO₄The decomposition temperature is 600-700 ℃, and the decomposition time is 3-6 h; preferably, the VOSO₄The decomposition temperature of (A) was 600 ℃.

Since the application uses pure V₂O₅And V₂O₃Does not involve other impurities, therefore, the M-phase VO prepared by the invention₂The purity of the product is more than 95 percent, and no other phase state exists.

The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.

Example 1

Weighing 50g of vanadium pentoxide and 41.21g of vanadium trioxide, placing the vanadium pentoxide and the vanadium trioxide into a corundum crucible, adding 71.67ml of sulfuric acid with the mass fraction of 98%, uniformly mixing and stirring the vanadium pentoxide and the vanadium trioxide, placing the mixture into an atmosphere furnace, slowly introducing argon, keeping the temperature for 2.5 hours after the temperature of the atmosphere furnace is raised to 80 ℃, continuing to raise the temperature to 600 ℃ after the first-stage heat preservation is finished, and keeping the temperature for 6 hours. Stopping heating, continuously introducing argon to the atmosphere furnace, cooling to room temperature, taking out a sample to obtain VO₂(M), wherein the M phase product purity is greater than 95%.

Example 2

50g of vanadium pentoxide and 37.46g of vanadium trioxide are weighed and placed in a corundum crucible, 114ml of sulfuric acid with the mass fraction of 98% is added into the corundum crucible, and the three are mixed and stirredAnd after the mixture is uniform, placing the mixture in an atmosphere furnace, slowly introducing argon, keeping the temperature for 1h after the temperature of the atmosphere furnace is raised to 200 ℃, continuing to raise the temperature to 700 ℃ after the first-stage heat preservation is finished, and keeping the temperature for 3 h. Stopping heating, continuously introducing argon to the atmosphere furnace, cooling to room temperature, taking out a sample to obtain VO₂(M) a differential thermal profile of fig. 1, an X-ray diffraction pattern of fig. 2; the purity of the M phase product in this example was greater than 95%.

Example 3

Weighing 50g of vanadium pentoxide and 34.34g of vanadium trioxide, placing the vanadium pentoxide and the vanadium trioxide into a corundum crucible, adding 87.59ml of sulfuric acid with the mass fraction of 98%, uniformly mixing and stirring the vanadium pentoxide and the vanadium trioxide, placing the mixture into an atmosphere furnace, slowly introducing argon, keeping the temperature for 1.8h after the temperature of the atmosphere furnace is raised to 150 ℃, continuing to raise the temperature to 650 ℃ after the first-stage heat preservation is finished, and keeping the temperature for 4 h. Stopping heating, continuously introducing argon to the atmosphere furnace, cooling to room temperature, taking out a sample to obtain VO₂(M), wherein the M phase product purity is greater than 95%.

Claims

1. Preparation of VO by solid phase method₂A method of phase change material, comprising the steps of:

2. VO preparation by solid phase method according to claim 1₂A method of phase change materials, characterized by: the V is₂O₅And V₂O₃The molar ratio of (A) is 1.0-1.2: 1; preferably 1: 1.

3. preparation of VO by solid phase method according to claim 1 or 2₂A method of phase change materials, characterized by: the molar ratio of the sulfuric acid to the total vanadium in the raw material is n (H)₂SO₄): n (TV) 1.2 to 2.0: 1; preferably 1.2: 1.

4. the solid phase method according to any one of claims 1 to 3Preparation of VO₂A method of phase change materials, characterized by: the mass fraction of the sulfuric acid is 50-98%.

5. VO prepared by the solid phase method according to any one of claims 1 to 4₂A method of phase change materials, characterized by: said generating VOSO₄The reaction temperature is 80-200 ℃, and the reaction time is 1-2.5 h; preferably, the generation of VOSO₄The reaction temperature of (2) was 140 ℃.

6. VO prepared by the solid phase method according to any one of claims 1 to 5₂A method of phase change materials, characterized by: the VOSO₄The decomposition temperature is 600-700 ℃, and the decomposition time is 3-6 h; preferably, the VOSO₄The decomposition temperature of (A) was 600 ℃.