CN110885095A - Method for preparing porous calcium titanate based on deep eutectic solvent - Google Patents

Abstract

The invention relates to a method for preparing porous calcium titanate based on a deep eutectic solvent, and belongs to the field of inorganic non-metallic materials. The method for porous calcium titanate is carried out according to the following steps: mixing the hydrogen bond acceptor and the hydrogen bond donor in a molar ratio of 1-1.5:1-3 to obtain a deep eutectic solvent; Solid ratio: The calcium-containing substance and titanium dioxide are added into the deep eutectic solvent, and mixed at 20-60° C. for 1-5 h to obtain a mixed solution; wherein, the molar ratio of the calcium-containing substance and the titanium dioxide is 1:1; the calcium-containing substance is Calcium oxide or calcium hydroxide: mix the obtained mixed solution with water in a volume ratio of 1:5-20, stand for precipitation, and filter to obtain a solid; 875～950℃, calcined for 3～5h, and then cooled to obtain porous calcium titanate powder. The method for the porous calcium titanate of the present invention can be carried out at a lower temperature.

Description

Method for preparing porous calcium titanate based on deep eutectic solvent

technical field

The invention relates to a method for preparing porous calcium titanate based on a deep eutectic solvent, and belongs to the field of inorganic non-metallic materials.

Background technique

Calcium titanate is a typical representative of perovskite oxides, and its ideal structure is generally cubic or octahedral. As an inorganic non-metallic material, it is widely used in photocatalysis, dielectric properties, optical properties, electricity, biological materials and other fields due to its unique structure, good stability, biocompatibility, abundant raw materials and low preparation cost. It is also of great significance in basic research and practical applications, and is very important for basic research and practical applications in many disciplines, including geology, solid-state chemistry, materials science, electrical engineering, and biotechnology. At present, perovskite oxides have shown many special properties in the fields of optics, electricity, biology, etc., and have become a research hotspot of functional oxide materials. At present, the traditional methods commonly used to prepare calcium titanate powder are solid-phase synthesis method and solvothermal method. Among them, the solid-phase synthesis method is controlled by the solid-phase diffusion in the reaction, which requires a higher temperature and a long reaction time, and has disadvantages such as large energy consumption, uneven particle size, and difficult to control the microstructure, and the obtained powder products are easy to be obtained. Agglomeration requires further crushing, grinding and other processes, which is easy to introduce impurities and other problems. The solvothermal method is to carry out the relevant chemical reaction under high temperature and high pressure. Although the reaction temperature is relatively low, the solvent used is usually an organic solvent and the reaction process usually requires the use of an autoclave, which causes the production process to cause harm to the environment. It can be seen that the need for a method for preparing calcium titanate which is environmentally friendly, simple in process flow and low in cost is particularly important.

At present, calcium titanate materials are usually prepared by using calcium chloride and titanium oxide as raw materials, and rarely using titanium oxide and calcium oxide as raw materials to prepare calcium titanate. The reason is that calcium titanate is directly prepared by using titanium oxide and calcium oxide as raw materials. "Research on the synthesis and calcination of the sintering method", Liaoning University of Science and Technology). In the prior art, a method for preparing calcium titanate using titanium oxide and calcium oxide as raw materials is also disclosed. After calcination, it is pulverized and ground. In this method, in order to reduce the sintering temperature of calcium titanate, additives are added to the raw materials of titanium oxide and calcium oxide, but even if other additives are added, the sintering temperature can only be reduced to 1350°C. The sintering temperature is still high.

SUMMARY OF THE INVENTION

The first technical problem to be solved by the present invention is to provide a method for preparing porous calcium titanate by using titanium oxide and calcium oxide as raw materials with a low sintering temperature.

The method for preparing porous calcium titanate based on deep eutectic solvent is carried out according to the following steps:

a. Preparation of a deep eutectic solvent: mixing the hydrogen bond acceptor and the hydrogen bond donor according to a molar ratio of 1-1.5:1-3 to obtain a deep eutectic solvent; wherein the hydrogen bond acceptor is a quaternary ammonium salt or betaine; the hydrogen bond donor is a carboxylic acid;

b. Dissolution of raw materials: add calcium-containing substances and titanium dioxide into a deep eutectic solvent at a liquid-solid ratio of 1:4-30, and mix at 20 to 60 ° C for 1-5 hours to obtain a mixed solution; wherein, calcium-containing substances The molar ratio with titanium dioxide is 1:1; the calcium-containing substance is calcium oxide or calcium hydroxide;

c, solution dilution and precipitation: the mixed solution obtained in step b is mixed with water in a volume ratio of 1:5-20, set aside for precipitation, and filtered to obtain a solid;

d. Calcination: calcining the solid material, controlling the heating rate to 2-5°C/min to raise the temperature to 875-950°C, calcining for 3-5 hours, and then cooling to room temperature to obtain porous calcium titanate powder.

Preferably, in step a: the hydrogen bond acceptor is a quaternary ammonium salt; more preferably, the quaternary ammonium salt is at least one of choline chloride and benzyltriethylammonium chloride; most preferably , the hydrogen bond acceptor is choline chloride.

Preferably, in step a: the hydrogen bond donor is oxalic acid, malic acid, citric acid or succinic acid; more preferably, the hydrogen bond donor is oxalic acid.

Preferably, in step a: the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1-2; more preferably, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:2.

Preferably, in step b: the particle size of the calcium-containing substance is less than or equal to 100 mesh, and the particle size of the titanium dioxide is less than or equal to 100 mesh.

Preferably, in step b: the liquid-solid ratio is 1:10-15; preferably, the liquid-solid ratio is 1:10.

Preferably, in step b: the calcium-containing substance and titanium dioxide are added to the deep eutectic solvent, and the mixture is uniformly mixed at 40-60°C.

Preferably, in step b: the temperature is 50° C., and the mixing time is 1-5 h; more preferably, the mixing time is 1-2 h.

Preferably, in step b: the mixing is carried out by stirring, and the stirring speed is controlled at 50-400 rpm; more preferably, the stirring speed is 100-400 rpm.

Preferably, in step c, the mixed solution prepared in step b is mixed with water in a volume ratio of 1:10-20.

Preferably, in step c, the precipitation time is 2-4h.

Preferably, in step d, the temperature is raised to 875-925° C. and calcined for 4-5 hours.

The present invention also provides a porous calcium titanate.

The porous calcium titanate is prepared by using the deep eutectic solvent to prepare the porous calcium titanate.

Compared with the prior art, the beneficial effects of the present invention:

1. Using a deep eutectic solvent to dissolve calcium oxide and titanium dioxide, adding water to precipitate and calcining to obtain porous calcium titanate powder, compared with the traditional process, it has the advantages of being environmentally friendly, relatively low reaction temperature, and wide source of raw materials.

2. The low eutectic solvent used is a green chemical solvent. Compared with pyrrole, pyridine and other ionic liquids, the used deep eutectic solvent is simple in synthesis and low in price.

3. The porous calcium titanate prepared by the method of the present invention has high yield, and the yield is ≥99.3%.

Description of drawings

Figure 1 is the XRD pattern of the product of Example 1.

Figure 2 is a SEM image of the product of Example 1.

Detailed ways

The first technical problem to be solved by the present invention is to provide a method for preparing porous calcium titanate by using titanium oxide and calcium oxide as raw materials with a low sintering temperature.

The method for preparing porous calcium titanate based on deep eutectic solvent is carried out according to the following steps:

a. Preparation of a deep eutectic solvent: mixing the hydrogen bond acceptor and the hydrogen bond donor according to a molar ratio of 1-1.5:1-3 to obtain a deep eutectic solvent; wherein the hydrogen bond acceptor is a quaternary ammonium salt or betaine; the hydrogen bond donor is a carboxylic acid;

b. Dissolution of raw materials: add calcium-containing substances and titanium dioxide into a deep eutectic solvent at a liquid-solid ratio of 1:4-30, and mix at 20 to 60 ° C for 1-5 hours to obtain a mixed solution; wherein, calcium-containing substances The molar ratio with titanium dioxide is 1:1; the calcium-containing substance is calcium oxide or calcium hydroxide;

c, solution dilution and precipitation: the mixed solution obtained in step b is mixed with water in a volume ratio of 1:5-20, set aside for precipitation, and filtered to obtain a solid;

d. Calcination: calcining the solid material, controlling the heating rate to 2-5°C/min to raise the temperature to 875-950°C, calcining for 3-5 hours, and then cooling to room temperature to obtain porous calcium titanate powder.

A deep eutectic solvent is a eutectic mixture composed of compounds such as hydrogen bond donors and hydrogen bond acceptors in a certain stoichiometric ratio. The deep eutectic solvent used in this patent has the advantages of wide electrochemical window, good solubility and conductivity, low vapor pressure and good physical and chemical stability. Compared with traditional solvents, it has the advantages of low vapor pressure, good solubility and good physical and chemical stability.

The invention uses a deep eutectic solvent as a solvent to prepare calcium titanate, which not only reduces the sintering temperature, but also prepares porous calcium titanate with controllable morphology and size. Therefore, using deep eutectic solvent as a solvent to prepare calcium titanate with controllable morphology and size has broad application prospects.

If the deep eutectic solvent of the present invention is not used, calcium oxide and titanium oxide are directly calcined at 875-950° C. for 3-5 hours, and calcium titanate cannot be obtained.

Preferably, in step a: the hydrogen bond acceptor is a quaternary ammonium salt; more preferably, the quaternary ammonium salt is at least one of choline chloride and benzyltriethylammonium chloride; most preferably , the hydrogen bond acceptor is choline chloride.

Preferably, in step a: the hydrogen bond donor is oxalic acid, malic acid, citric acid or succinic acid; more preferably, the hydrogen bond donor is oxalic acid.

Preferably, in step a: the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1-2; more preferably, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:2.

Wherein, in order to improve the purity of the obtained product, the molar ratio of calcium-containing substance and titanium dioxide is 1:1.

Preferably, in step b: the particle size of the calcium-containing substance is less than or equal to 100 mesh, and the particle size of the titanium dioxide is less than or equal to 100 mesh.

In step b, the raw material dissolving step: adding the calcium-containing substance and titanium dioxide into the deep eutectic solvent at a liquid-solid ratio of 1:4-30, mixing, controlling the temperature to be 20-60°C, and the dissolving time to 1-5h. The liquid-solid ratio is the liquid-solid mass ratio, and the liquid-solid ratio=the mass of the deep eutectic solvent/(the mass of the calcium-containing substance+the mass of the titanium dioxide).

Preferably, in step b: the liquid-solid ratio is 1:10-15; preferably, the liquid-solid ratio is 1:10.

Wherein, in step b: the temperature is 50°C, and the mixing time is 1-5h; if the mixing time is too short, the calcium-containing substance is not fully dissolved, and the mixing with titanium dioxide is uneven. More preferably the mixing time is 1-2h.

In order to make the product mix more uniform, preferably, in step b: the mixing is carried out by stirring, and the stirring speed is controlled at 50-400 rpm.

Preferably, in step c, the precipitation is left to stand for 2-5 hours. If the time is too short, part of the solid phase will not settle down; it will affect the yield of the product; if the time is too long, the time for preparing the product will be prolonged. Preferably, in step c: the precipitation time is 2-4h.

In the step d of the present invention, the calcination temperature needs to be 875-950°C, and the calcination time is 3-5h; if the calcination temperature is too low, the product will not obtain calcium titanate; if the calcination time is too short, the product will be impure and not fully decomposed. . Preferably, in step d, the temperature is raised to 875-925° C. and calcined for 4-5 hours.

Wherein, in step d, the heating rate is controlled to be 2-5° C./min. If the heating rate is too fast, the particle size of the powder will be larger and the size will be uneven.

Under the calcination conditions of the present invention, calcium titanate having a porous structure can be obtained.

The present invention also provides a porous calcium titanate.

The porous calcium titanate is prepared by using the deep eutectic solvent to prepare the porous calcium titanate.

The specific embodiments of the present invention will be further described below with reference to the examples, but the present invention is not limited to the scope of the described examples.

Example 1

The method for preparing porous calcium titanate based on a deep eutectic solvent, the specific steps are as follows:

(1) firstly prepare a deep eutectic solvent, be 1:1.5 with choline chloride and oxalic acid according to mol ratio to be placed in a beaker and mix to form a deep eutectic solvent for subsequent use;

(2) Grinding and mixing calcium oxide and titanium dioxide. Then, the ground and mixed calcium oxide and titanium dioxide were added to the deep eutectic solvent at a liquid-solid ratio of 1:10 for dissolution. The stirring speed was controlled at 200 rpm, the temperature was 40 °C, and the dissolution time was 2h;

(3) Add the solution of dissolving raw materials into deionized water of 10 times the volume and let stand for precipitation for 2h;

(4) Finally, the water-added solution is left to stand for precipitation and then filtered, and the resulting powder is calcined in a tube furnace, and the heating rate is controlled to 2 °C/min, the temperature is raised to 900 °C, and the temperature is naturally cooled to room temperature for 3 hours. Calcium titanate powder can be obtained, and the purity is 99.5% after testing.

The XRD pattern and SEM pattern of the product of this example are shown in FIG. 1 and FIG. 2 . It can be seen from Fig. 2 that the obtained product forms a pore structure, so the obtained product is porous calcium carbonate.

Example 2

The method for preparing porous calcium titanate based on a deep eutectic solvent, the specific steps are as follows:

(1) first prepare a deep eutectic solvent, be that choline chloride and oxalic acid are placed in a beaker according to a mol ratio of 1:1 to mix and form a deep eutectic solvent for subsequent use;

(2) Grinding and mixing calcium oxide and titanium dioxide. Then add the ground and mixed calcium oxide and titanium dioxide into a deep eutectic solvent at a liquid-solid ratio of 1:15 for dissolution, the stirring speed is controlled at 100 rpm, the temperature is 50 °C, and the dissolution time is 2h;

(3) Add the solution of dissolving raw materials into deionized water of 10 times the volume and let stand for precipitation for 2h;

(4) Finally, the water-added solution is left to stand for precipitation and then filtered, the resulting powder is calcined in a tube furnace, the temperature rise rate is controlled to 2°C/min, the temperature is raised to 875°C, and the temperature is naturally cooled to room temperature for 5 hours and taken out, that is, Porous calcium titanate powder with a purity of 99.6% can be obtained.

Example 3

The method for preparing porous calcium titanate based on a deep eutectic solvent, the specific steps are as follows:

(1) first prepare a deep eutectic solvent, be 1:2 with choline chloride and oxalic acid to be placed in a beaker to mix and then form a deep eutectic solvent for subsequent use;

(2) Grinding and mixing calcium oxide and titanium dioxide. Then, the ground and mixed calcium oxide and titanium dioxide were added to the deep eutectic solvent at a liquid-solid ratio of 1:10 for dissolution. The stirring speed was controlled at 400 rpm, the temperature was 50 °C, and the dissolution time was 1 h;

(3) Add the solution of dissolving raw materials into deionized water of 10 times volume and let stand for precipitation for 4h;

(4) Finally, the water-added solution is left to stand for precipitation and then filtered, and the resulting powder is calcined in a tube furnace, and the temperature rise rate is controlled to 5°C/min, the temperature is raised to 925°C, and the temperature is naturally cooled to room temperature for 4 hours and taken out, that is, Porous calcium titanate powder with a purity of 99.7% can be obtained.

Example 4

The method for preparing porous calcium titanate based on a deep eutectic solvent, the specific steps are as follows:

(1) first prepare a deep eutectic solvent, be that choline chloride and oxalic acid are placed in a beaker according to a mol ratio of 1:1 to mix and form a deep eutectic solvent for subsequent use;

(2) Grinding and mixing calcium oxide and titanium dioxide. Then add the ground and mixed calcium oxide and titanium dioxide into a deep eutectic solvent at a liquid-solid ratio of 1:15 for dissolution, the stirring speed is controlled at 50 rpm, the temperature is 60 °C, and the dissolution time is 5h;

(3) Add the solution of dissolving raw materials into deionized water of 10 times volume and let stand for precipitation for 3h;

(4) Finally, the water-added solution was allowed to stand for precipitation and then filtered. The resulting powder was calcined in a tube furnace, and the temperature was controlled at a rate of 2°C/min, and the temperature was raised to 900°C. The porous calcium titanate powder with a purity of 99.3% can be obtained.

Example 5

The method for preparing porous calcium titanate based on a deep eutectic solvent, the specific steps are as follows:

(1) firstly prepare a deep eutectic solvent, be 1:1.5 with choline chloride and oxalic acid according to mol ratio to be placed in a beaker and mix to form a deep eutectic solvent for subsequent use;

(2) Grinding and mixing calcium oxide and titanium dioxide. Then, the ground and mixed calcium oxide and titanium dioxide were added to the deep eutectic solvent at a liquid-solid ratio of 1:10 for dissolution, the stirring speed was controlled at 200 rpm, the temperature was 50 °C, and the dissolution time was 4h;

(3) adding the solution of dissolving raw materials into deionized water of 20 times the volume and allowing to stand for precipitation for 2h;

(4) Finally, the water-added solution was left to stand for precipitation, and then filtered. The resulting powder was calcined in a tube furnace, and the temperature was controlled at a rate of 5°C/min, and the temperature was raised to 950°C. The porous calcium titanate powder with a purity of 99.4% can be obtained.

Claims (10)

1. The method for preparing the porous calcium titanate based on the eutectic solvent is characterized by comprising the following steps of:

a. preparing a eutectic solvent: uniformly mixing a hydrogen bond acceptor and a hydrogen bond donor according to the molar ratio of 1-1.5:1-3 to obtain a eutectic solvent; wherein the hydrogen bond acceptor is a quaternary ammonium salt or betaine; the hydrogen bond donor is a carboxylic acid;

b. dissolving raw materials: adding a mixture containing calcium and titanium dioxide into a eutectic solvent according to a liquid-solid ratio of 1:4-30, and mixing for 1-5h at 20-60 ℃ to obtain a mixed solution; wherein the molar ratio of the calcium-containing substance to the titanium dioxide is 1: 1; the calcium-containing substance is calcium oxide or calcium hydroxide;

c. solution dilution and precipitation: uniformly mixing the mixed solution prepared in the step b with water according to the volume ratio of 1:5-20, standing, precipitating and filtering to obtain a solid substance;

d. and (3) calcining: and calcining the solid matter, controlling the heating rate to be 2-5 ℃/min, heating to 875-950 ℃, calcining for 3-5 h, and cooling to room temperature to obtain the porous calcium titanate powder.

2. The method for preparing porous calcium titanate according to claim 1, wherein in the step a: the hydrogen bond acceptor is quaternary ammonium salt; preferably, the quaternary ammonium salt is at least one of choline chloride and benzyltriethylammonium chloride; more preferably, the hydrogen bond acceptor is choline chloride.

3. The method for preparing porous calcium titanate according to claim 1 or 2, wherein in the step a: the hydrogen bond donor is oxalic acid, malic acid, citric acid or succinic acid; preferably, the hydrogen bond donor is oxalic acid.

4. The method for preparing porous calcium titanate according to claim 1, wherein in the step a: the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1: 1-2; preferably, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1: 2.

5. The method for preparing porous calcium titanate according to claim 1, wherein in the step b: the granularity of the calcium-containing substance is less than or equal to 100 meshes, and the granularity of the titanium dioxide is less than or equal to 100 meshes.

6. The method for preparing porous calcium titanate according to claim 1, wherein in the step b: the liquid-solid ratio is 1: 10-15; preferably, the liquid-to-solid ratio is 1: 10.

7. The method for preparing porous calcium titanate according to claim 1, wherein in the step b: the temperature is 50 ℃, and the mixing time is 1-5 h; the mixing time is preferably 1-2 h.

8. The method for preparing porous calcium titanate according to claim 1, wherein in the step c: the precipitation time is 2-4 h.

9. The method for preparing porous calcium titanate according to claim 1, wherein in step d: heating to 875-925 ℃ and calcining for 4-5 h.

10. A porous calcium titanate produced by the method for producing a porous calcium titanate according to any one of claims 1 to 9.

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