CN116239133A - Preparation method of beryllium oxide - Google Patents

Abstract

The invention relates to a preparation method of beryllium oxide, which comprises the following steps: (1) premixing: mixing beryllium salt with the eutectic solvent to obtain a mixture A; (2) coating the ionic liquid: mixing the mixture A in the step (1) with an ionic liquid to obtain a mixture B; (3) carbonization: carbonizing the mixture B obtained in the step (2); (4) roasting: roasting the carbonized product in the step (3) to obtain beryllium oxide. According to the invention, through the pre-coating of the eutectic solvent, the effect of coating the beryllium salt and the outermost ionic liquid can be pulled up, so that the interaction force among the beryllium salt, the eutectic solvent and the ionic liquid is improved, the ionic liquid is coated more tightly, and the particle size range of beryllium oxide is reduced.

Description

Preparation method of beryllium oxide

Technical Field

The invention relates to the technical field of nano particles, in particular to a preparation method of beryllium oxide.

Background

Beryllium oxide (BeO) has the characteristics of high melting point, high strength, low dielectric constant, good packaging process adaptability and the like, is a mainstream ceramic material prepared from high-heat-conductivity components in high-power integrated circuits, semiconductor devices, high-power microwave vacuum devices and nuclear reactors, and has wide application in the fields of nuclear technology, microelectronics, vacuum electronics technology, microwave technology and photoelectron technology. Although BeO ceramics are widely applied to a plurality of fields, the sintering temperature is very high when common powder is adopted to prepare the BeO ceramics because the melting point of the BeO is as high as (2570+/-20), so that the BeO ceramic material with high purity, high compactness and excellent performance is difficult to obtain. It has been found that the use of nano-powders for the preparation of ceramic materials not only reduces the sintering temperature, but also contributes to the improvement of the properties of the ceramic materials. Therefore, the research and preparation of the nano BeO are very necessary and have application prospect.

At present, the preparation method of the nano BeO comprises a microemulsion method, a gel method and the like, but has the defects of complex process, the use of various auxiliary agents and a large amount of organic solvents, high decomposition temperature of precursors (such as beryllium sulfate and beryllium hydroxide) and the like, and the particle size of the nano BeO particles still has a reduced space. The method which is more commonly used in industry comprises the steps of extracting beryllium hydroxide from andalusite, then carrying out thermal decomposition to obtain the beryllium hydroxide, or dissolving industrial beryllium hydroxide in sulfuric acid to generate beryllium sulfate solution, filtering, precipitating and roasting to obtain beryllium oxide powder, and finally grinding the beryllium oxide powder to nano-scale through a nano grinder.

CN114671444 a discloses a process for preparing beryllium oxide by using an ionic liquid carbon coating method, and the size of beryllium oxide particles is regulated and controlled by combining the electrostatic action and the space stabilization action of the ionic liquid, so that beryllium oxide nano particles with small particle size are obtained. However, the viscosity of the ionic liquid is larger, the uniformity of the thickness of the coating layer is not easy to control, the homogenization coating process is realized by adjusting the step stirring process and the step roasting process, the process is complex, the dosage of the ionic liquid is more, the cost is higher, and the method is not suitable for industrialization.

In view of the above, it is important to develop a method for preparing beryllium oxide with uniform particle size, which can be produced in a large scale.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide beryllium oxide and a preparation method thereof, and the beryllium oxide prepared by the method has uniform particle size, further reduces agglomeration, can reduce the use amount of ionic liquid and simplifies the production process flow.

To achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for preparing beryllium oxide, the method comprising the steps of:

(1) Premixing: mixing beryllium salt with the eutectic solvent to obtain a mixture A;

(2) Coating an ionic liquid: mixing the mixture A in the step (1) with an ionic liquid to obtain a mixture B;

(3) Carbonizing: carbonizing the mixture B obtained in the step (2);

(4) Roasting: roasting the carbonized product obtained in the step (3) to obtain beryllium oxide.

In the step (1), the beryllium salt comprises beryllium sulfate and beryllium nitrate.

The mass ratio of the eutectic solvent to the beryllium salt is (0.5-2): 1, preferably 1:1, a step of; the eutectic solvent can be used as a solvent and a stabilizer, and is beneficial to subsequent uniform carbonization. The eutectic solvent and beryllium salt can be ensured to be mixed and dissolved in the range, and the 'pre-coating' can be realized.

The eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is selected from choline chloride, betaine, L-lysine or L-arginine; the hydrogen bond donor is selected from glycerol or ethylene glycol.

Preferably, the eutectic solvent is an amino acid eutectic solvent, i.e. the hydrogen bond acceptor is selected from L-lysine or L-arginine.

Hydrogen bond acceptor: the molar ratio of the hydrogen bond donor is 1 (3-5).

Preferably, the mixing in the step (1) means stirring at 30-80 ℃ for 1-2h.

In the invention, the eutectic solvent in the step (1) and beryllium salt form premixing, and the eutectic solvent has good solubility, lower viscosity and good solubility and dispersibility of the beryllium salt, especially lysine and arginine containing amino and carboxyl, is beneficial to regulating the pH value of a system, so that the premixing process is more stable and uniform, particle aggregation in the roasting process is avoided, and the particle size distribution is narrow.

Furthermore, the invention can 'pull up' the effect of beryllium salt and the coating of the outermost ionic liquid through the premixing of the eutectic solvent, and improves the interaction force among the beryllium salt, the eutectic solvent and the ionic liquid, thereby enabling the coating of the ionic liquid to be more compact and reducing the particle size range of beryllium oxide.

The molar ratio of the ionic liquid to the beryllium salt in the step (2) is (0.5-1): 1, and the ionic liquid can be fully coated within the range.

The mixing in the step (2) means that stirring is carried out for 1-2h at 30-80 ℃ under inert atmosphere.

The invention adopts eutectic solvent to mix so as to form a 'pre-coating', and then carries out secondary coating of the ionic liquid, so that effective coating can be formed by using a small amount of ionic liquid, the using amount of the ionic liquid is greatly reduced, complicated step-by-step stirring and step-by-step roasting processes are not needed, and the process flow is simplified.

In the step (2), after the mixture A is mixed with the ionic liquid, a rotary evaporation step can be further included to concentrate the solvent.

In the step (3), the molar concentration of the ionic liquid solution is 0.1-1.0moL/L, preferably 0.1-0.2moL/L; the solvent is water.

Preferably, the ionic liquid is one or more of imidazole ionic liquid, pyridine ionic liquid and quaternary ammonium salt ionic liquid, preferably imidazole ionic liquid, and is selected from 1-ethyl-3-methylimidazole acetate, 1-octyl-3-methylimidazole chloride, 1-hexyl-3-methylimidazole chloride, 1-butyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole diethyl phosphate or 1-ethyl-3-methylimidazole tetrafluoroborate.

In step (3), preferably, the carbonization is performed in an inert atmosphere.

Preferably, the inert atmosphere comprises nitrogen, argon, helium.

Preferably, the carbonization temperature is 400-550 ℃.

Preferably, the carbonization temperature rise rate is 5-10 ℃/min.

Preferably, after the temperature is raised to the carbonization temperature, the carbonization is completed by maintaining for 2 to 4 hours.

Preferably, the carbonization further comprises cooling to 10-40 ℃, e.g. 15 ℃, 20 ℃, 25 ℃,30 ℃, 35 ℃ etc., to obtain beryllium salt coated with a double carbon layer.

In the step (4), the roasting temperature is 450-700 ℃ and the roasting time is 1-4h, so as to obtain beryllium oxide.

Preferably, the firing rate is 5-15 ℃/min, such as 6 ℃/min, 8 ℃/min, 10 ℃/min, 12 ℃/min, 14 ℃/min, etc.

In a second aspect, the present invention provides a beryllium oxide prepared by the method of the first aspect.

Preferably, the mean particle size of the beryllium oxide is less than 15nm, preferably less than 10nm.

The invention has the following beneficial effects:

(1) According to the invention, through premixing of the eutectic solvent, the effect of coating the beryllium salt and the outermost ionic liquid can be pulled up, and the interaction force among the beryllium salt, the eutectic solvent and the ionic liquid is improved, so that the ionic liquid is coated more tightly, and the particle size range of beryllium oxide is reduced.

(2) The invention forms premixing with beryllium salt through the amino acid eutectic solvent, which is beneficial to adjusting the pH value of the system, so the pre-coating process is more stable and uniform, and particle aggregation in the roasting process is avoided.

(3) The invention adopts eutectic solvent for premixing and then ionic liquid for coating, thereby greatly reducing the use amount of ionic liquid, obtaining beryllium oxide products with uniform particle size without complex step stirring and step roasting processes, simplifying the process and being beneficial to industrialized production.

Drawings

FIG. 1 is a high resolution transmission electron microscope image of beryllium oxide obtained in example 1.

Detailed Description

The method for preparing beryllium oxide according to the present invention will be further described with reference to specific examples and drawings, but it should be understood that the scope of the present invention is not limited to the following examples.

Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present invention.

The materials and reagents used in the invention are all commercial products.

Example 1

The embodiment provides a preparation method of beryllium oxide, which comprises the following steps:

(1) Taking 2.1g of beryllium sulfate, wherein the mass ratio of the beryllium sulfate to the eutectic solvent (L-lysine: glycerol molar ratio is 1:3) is 1:1, mixing and stirring for 1h at 50 ℃, and cooling and taking out after the completion of the mixing to obtain a mixture A;

(2) According to the mole ratio of the 1-octyl-3-methylimidazole chloride ionic liquid to the beryllium sulfate of 0.5:1, 2.3g of ionic liquid is taken and dissolved in 20ml of water, then the ionic liquid solution is added into the mixture A, and the mixture A is concentrated by rotary evaporation to obtain a mixture B;

transferring the mixture B into a polytetrafluoroethylene lining of a high-pressure reaction kettle, charging nitrogen until the pressure is 1.0MPa, heating to 70 ℃, stirring for 3 hours, and cooling and taking out after the completion of the stirring;

(3) Placing the product obtained in the step (2) into a quartz boat, placing into a box-type resistance furnace, setting the temperature to 400 ℃, heating at a speed of 10 ℃/min, and cooling after 3 hours;

(4) Roasting the product obtained in the step (3) in a muffle furnace, heating to 600 ℃ at a heating rate of 10 ℃/min at room temperature, and keeping for 2h; obtaining the beryllium oxide.

Example 2

Eutectic solvent L-lysine in step (1): the molar ratio of glycerol is 1:4.

other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 3

Eutectic solvent L-arginine in step (1): the molar ratio of glycerol is 1:5.

other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 4

Eutectic solvent L-arginine in step (1): the molar ratio of ethylene glycol is 1:4.

other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 5

In the step (1), the mass ratio of beryllium sulfate to the eutectic solvent (L-lysine: glycerol molar ratio is 1:3) is 1:2, mixing.

Other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 6

In the step (1), the eutectic solvent is choline chloride: the molar ratio of the ethylene glycol is 1:3.

Other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 7

In the step (2), the molar ratio of the 1-octyl-3-methylimidazole chloride ionic liquid to the beryllium sulfate is 1:1, 4.6g of ionic liquid was taken and dissolved in 18ml of water, and then the ionic liquid solution was added to mixture A to obtain mixture B.

Other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 8

In the step (3), setting the temperature of a box-type resistance furnace to be 500 ℃, keeping the temperature rising rate to be 10 ℃/min, and cooling after keeping for 2 hours to obtain beryllium sulfate nano-particles wrapped by a carbon layer;

in the step (4), the room temperature is raised to 650 ℃, the heating rate is 10 ℃/min, and the temperature is kept for 1.5h.

Other steps were the same as in example 1, and beryllium oxide was finally obtained.

Example 9

In step (2), 2g of 1-hexyl-3-methylimidazolium chloride was used instead of 1-octyl-3-methylimidazolium chloride ionic liquid.

The rest is the same as in example 1, and beryllium oxide is finally obtained.

Example 10

In the step (2), 1.7g of 1-ethyl-3-methylimidazole acetate is used for replacing the 1-octyl-3-methylimidazole chloride ionic liquid. The rest is the same as in example 1, and beryllium oxide is finally obtained.

Comparative example 1

The comparative example provides a method for preparing beryllium oxide, which comprises the following steps:

(1) The molar ratio of the 1-octyl-3-methylimidazole chloride ionic liquid to the beryllium sulfate is 2.5:1, mixing to obtain a mixture A;

(3) Transferring the mixture A into a polytetrafluoroethylene lining of a high-pressure reaction kettle, charging nitrogen until the pressure is 1.0MPa, heating to 60 ℃, stirring for 3 hours, and cooling and taking out after the completion of the stirring to obtain ionic liquid stable beryllium sulfate nano-particles;

(4) Placing ionic liquid stabilized beryllium sulfate nano-particles into a quartz boat, placing into a box-type resistance furnace, setting the temperature to 400 ℃, the heating rate to 10 ℃/min, and cooling after 3 hours to obtain carbon layer coated beryllium sulfate nano-particles;

(5) In a muffle furnace, roasting beryllium sulfate nano-particles wrapped by a carbon layer, and setting a programmed temperature: heating the room temperature to 450 ℃, keeping the temperature rising speed at 10 ℃/min for 1h; heating to 600 ℃ at the temperature of 450 ℃ and the heating rate of 10 ℃/min, and keeping for 1h to obtain beryllium oxide.

Nanometer beryllium oxide performance test

Beryllium oxide prepared in examples and comparative examples was tested as follows:

(1) Appearance morphology: obtaining an electron microscope image by adopting a high-resolution transmission electron microscope, and observing the apparent morphology of the nano particles;

(2) Average particle size and particle size distribution: the average particle size D50 and the particle size distribution (D90-D10)/D50 of the beryllium oxide were measured according to an electron microscope and the results are shown in Table 1.

TABLE 1

As can be seen from the data of Table 1, the mean particle diameter D50 of beryllium oxide prepared in the examples of the present invention is within 12nm, the particle diameter distribution (D90-D10)/D50 is narrower, while the comparative example 1 of the prior art CN 114671444A method can control the particle diameter of nano beryllium oxide to 15nm, but the particle diameter distribution (D90-D10)/D50 is wider, the amount of ionic liquid is larger, and the roasting process is complicated.

As can be seen from examples 1 and 6, the pre-mixing treatment of the eutectic solvent can effectively reduce the particle size of beryllium oxide, wherein the amino acid eutectic solvent has better effect, is more beneficial to the stability of the system and has more uniform nano particle size.

The surface morphology is observed through the high-resolution transmission electron microscope image in fig. 1, the particle size of beryllium oxide particles in the embodiment 1 of the invention can reach about 10nm, and the particles are more uniformly dispersed without particle aggregation phenomenon. In summary, compared with the preparation method in the prior art, the preparation method provided by the invention can form double-coated nano particles, and the action of the eutectic solvent is utilized to improve the acting force between beryllium salt and ionic liquid, so that the prepared beryllium oxide has small particle size and concentrated particle size distribution, the aggregation of the nano particles can be effectively prevented, the technical barrier of the nano beryllium oxide with the particle size of 20nm in the prior art is broken through, the use amount of the ionic liquid is reduced, the process flow is simplified, and the industrial popularization can be realized.

The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims (9)

1. The preparation method of beryllium oxide is characterized by comprising the following steps:

(1) Premixing: mixing beryllium salt with the eutectic solvent to obtain a mixture A;

(2) Coating an ionic liquid: mixing the mixture A in the step (1) with an ionic liquid to obtain a mixture B;

(3) Carbonizing: b carbonizing the mixture obtained in the step (2);

(4) Roasting: roasting the carbonized product obtained in the step (3) to obtain beryllium oxide.

2. The method of claim 1, wherein in step (1), the beryllium salt comprises beryllium sulfate, beryllium nitrate; the mass ratio of the eutectic solvent to the beryllium salt is (0.5-2): 1, a step of; the mixing means that stirring is carried out for 1-2h at 30-80 ℃.

3. The method of preparing according to claim 2, wherein the eutectic solvent of step (1) comprises a hydrogen bond acceptor and a hydrogen bond donor; the hydrogen bond acceptor is selected from choline chloride, betaine, L-lysine or L-arginine; the hydrogen bond donor is selected from glycerol or ethylene glycol.

4. A method of preparation according to claim 3, wherein the eutectic solvent hydrogen bond acceptor is selected from L-lysine or L-arginine; hydrogen bond acceptor: the molar ratio of the hydrogen bond donor is 1 (3-5).

5. The method according to claim 1, wherein the molar ratio of ionic liquid to beryllium salt in step (2) is (0.5-1): 1;

in the step (2), the molar concentration of the ionic liquid solution is 0.1-1.0moL/L, preferably 0.1-0.2moL/L;

the mixing in the step (2) means that stirring is carried out for 1-2h at 30-80 ℃ under inert atmosphere.

6. The preparation method according to claim 5, wherein the ionic liquid is an imidazole ionic liquid, a pyridine ionic liquid or a quaternary ammonium salt ionic liquid;

preferably one or more of 1-ethyl-3-methylimidazole acetate, 1-octyl-3-methylimidazole chloride, 1-hexyl-3-methylimidazole chloride, 1-butyl-3-methylimidazole chloride, 1-allyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole diethyl phosphate or 1-ethyl-3-methylimidazole tetrafluoroborate.

7. The method of claim 1, wherein in step (3), the carbonization is performed in an inert atmosphere; the inert atmosphere comprises nitrogen, argon and helium; the carbonization temperature is 400-550 ℃, and the carbonization time is kept for 2-4 hours.

8. The method according to claim 1, wherein in the step (4), the baking temperature is 450-700 ℃ and the baking time is 1-4 hours;

the temperature rising rate of the roasting is 5-15 ℃/min.

9. The beryllium oxide produced by the method of any one of claims 1-8, wherein the mean particle size of the beryllium oxide is less than 15nm.

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