阅读说明：本技术 一种高催化效率的中空纳米氟化铝球及其制备方法 (Hollow nano aluminum fluoride ball with high catalytic efficiency and preparation method thereof ) 是由 余恺为 吴明洋 于 2021-09-18 设计创作，主要内容包括：本发明涉及一种高催化效率的中空纳米氟化铝球,所述中空纳米氟化铝球的内径为20nm-80nm,壁厚为30nm-60nm。本发明通过设计中空纳米氟化铝球的内外径比、及球壁厚度等参数,以获得更高的比表面积,利用中空纳米氟化铝球的活性中心、有限的孔隙空间和可调的传质速率等特点,能进一步可控的提升中空纳米氟化铝球材料对于含氟有机化合物合成的催化效率。(The invention relates to a hollow nano aluminum fluoride ball with high catalytic efficiency, wherein the inner diameter of the hollow nano aluminum fluoride ball is 20nm-80nm, and the wall thickness is 30nm-60 nm. The invention designs the inner-outer diameter ratio of the hollow nano aluminum fluoride ball, the thickness of the ball wall and other parameters to obtain higher specific surface area, and can further controllably improve the catalytic efficiency of the hollow nano aluminum fluoride ball material for synthesizing fluorine-containing organic compounds by utilizing the characteristics of the active center, the limited pore space, the adjustable mass transfer rate and the like of the hollow nano aluminum fluoride ball.)

1. A hollow nanometer aluminum fluoride ball with high catalytic efficiency is characterized in that: the inner diameter of the hollow nano aluminum fluoride ball is 20nm-80nm, and the wall thickness is 10nm-70 nm.

2. The high catalytic efficiency hollow nano-aluminum fluoride ball of claim 1, wherein: the inner diameter of the wall thickness of the hollow nano aluminum fluoride ball is 40-50nm, and the wall thickness is 40-50 nm.

3. The high catalytic efficiency hollow nano-aluminum fluoride ball of claim 1, wherein: the ratio of the inner diameter to the outer diameter of the hollow nano aluminum fluoride ball is 3: 8-5: 7.

4. the high catalytic efficiency hollow nano-aluminum fluoride ball of claim 3, wherein: the inner diameter ratio and the outer diameter ratio of the hollow nano aluminum fluoride ball are 4: 9-5: 9.

5. the high catalytic efficiency hollow nano-aluminum fluoride ball of claim 1, wherein: the BET specific surface area of the hollow nano aluminum fluoride ball is more than or equal to 1200m²/g。

6. The method for preparing hollow nano aluminum fluoride spheres as claimed in any one of claims 1 to 4, wherein the method comprises the following steps: the method comprises the following steps:

adding aluminum isopropoxide into ethanol, and stirring to obtain a uniform solution;

step two, adding the hard template (1) into the uniform solution prepared in the step one, continuously stirring and heating to volatilize ethanol and form dry powder, and forming a layer of uniform Al (OC) on the surface of the hard template (1)₃H₇）₃A film;

step three, exposing the dry powder prepared in the step two in the air, and after the dry powder absorbs the moisture in the air, performing hydrolytic polycondensation to form (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃A gel film;

step four, adding (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Placing the gel film in a muffle furnace, heating to 500-600 deg.C at (1-5) ° C/min, and performing heat treatment for 10-15H to obtain (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Conversion of gel film to amorphous Al₂O₃A membrane (2);

step five, adopting a fluorine-containing carbon source to react Al₂O₃Coating the film (2), gradually heating to 900-1100 ℃ in a protective atmosphere, and carbonizing for 1-3 h to obtain amorphous Al₂O₃The film (2) is converted into alpha-crystalline Al₂O₃A membrane (2);

step six, adding HF acid to Al₂O₃Fluorination of the membrane (2) to obtain a crystalline-like AlF₃And (3) etching the hard template (1) by using HF acid to prepare the hollow nano aluminum fluoride ball (4) with controllable inner and outer diameters.

7. The method for preparing the hollow nano aluminum fluoride ball according to claim 6, which is characterized in that: the hard template (1) is polystyrene latex particles, colloidal sol, carbon particles and SiO₂One or a combination of two or more of the particles.

8. The preparation method of the hollow nano aluminum fluoride ball of claim 7, which is characterized in that: the D50 particle size of the SiO2 particle is 20nm-80 nm.

9. The method for preparing the hollow nano aluminum fluoride ball according to claim 8, which is characterized in that: the D50 particle size of the SiO2 particle is 40nm-50 nm.

10. The method for preparing the hollow nano aluminum fluoride ball according to claim 6, which is characterized in that: the aluminum isopropoxide accounts for 10-50 wt%.

Technical Field

The invention relates to a hollow nano aluminum fluoride ball, in particular to a hollow nano aluminum fluoride ball with high catalytic efficiency and a preparation method thereof.

Background

Aluminum fluoride (AlF)₃) Aluminum fluoride is widely used in the preparation of fluorine-containing organic materials because it is a catalyst having strong Lewis acidity (Lewis) and can stably exist in an HF acid (hydrofluoric acid) atmosphere. The preparation of very high quality aluminum fluoride materials has been achieved in conventional preparation methods; however, in the existing preparation method, the fluorine atom (F) in the aluminum fluoride is coordinated with the aluminum atom (Al) in a regular octahedral structure due to the uncontrollable crystal growth, so that the aluminum atom is saturated in coordination; the regularity of atom coordination not only enables most types of aluminum fluoride to show low Lewis acidity, but also enables the specific surface area (the specific surface area refers to the total area of materials with unit mass, non-porous materials only have the outer surface area, and the specific surface area of porous materials is the sum of the outer surface area of the materials and the inner surface area of pores) to be mostly between 0.5 and 30m²(ii)/g; in practical application, the Lewis acidity of the heterogeneous catalyst is basically dependent on the specific surface area, so that the application field of the aluminum fluoride prepared by the conventional method is limited. The existing preparation method can only work from a plurality of aspects such as a reaction source, a coating structure and the like, so as to finally improve the properties such as the surface structure, the crystal orientation selection and the like of the aluminum fluoride; the prior art has not, however, been able to more thoroughly study the ability of aluminum fluoride to improve its catalytic performance over its internal and external surface ratios. Therefore, it is necessary to design the ratio of the inner diameter to the outer diameter of the hollow nano aluminum fluoride ball to improve the catalytic performance.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a hollow nano aluminum fluoride ball with high catalytic efficiency.

The purpose of the invention is realized as follows:

the hollow nano aluminum fluoride ball with high catalytic efficiency has an inner diameter of 20-80 nm and a wall thickness of 30-60 nm.

As a specific scheme, the inner diameter of the wall thickness of the hollow nano aluminum fluoride ball is 40-50nm, and the wall thickness is 40-50 nm.

As another specific scheme, the ratio of the inner diameter to the outer diameter of the hollow nano aluminum fluoride ball is 3: 8-5: 7, preferably 4: 9-5: 9.

in another specific embodiment, the BET specific surface area of the hollow nano aluminum fluoride ball is greater than or equal to 1200m²/g。

The preparation method of the hollow nano aluminum fluoride ball comprises the following steps:

adding aluminum isopropoxide into ethanol, and stirring to obtain a uniform solution;

step two, adding the hard template into the uniform solution prepared in the step one, continuously stirring and heating to volatilize ethanol and form dry powder, and forming a layer of uniform Al (OC) on the surface of the hard template₃H₇）₃A film;

step three, exposing the dry powder prepared in the step two in the air, and after the dry powder absorbs the moisture in the air, performing hydrolytic polycondensation to form (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃A gel film;

step four, adding (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Placing the gel film in a muffle furnace, heating to 500-600 deg.C at (1-5) ° C/min, and performing heat treatment for 10-15H to obtain (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Conversion of gel film to amorphous Al₂O₃A film;

step five, adopting a fluorine-containing carbon source to react Al₂O₃Coating the film, gradually heating to 900-1100 ℃ in a protective atmosphere, and carbonizing for 1-3 h to obtain amorphous Al₂O₃Film transformation to alpha crystalline Al₂O₃A film;

step six, adding HF acid to Al₂O₃Fluorination of the membrane to produce crystalline-like AlF₃The film and HF acid etch the hard template simultaneously to produce hollow cavity with controllable inner and outer diametersNanometer aluminum fluoride ball.

As a specific scheme, the hard template is polystyrene latex particles, colloidal sol, carbon particles and SiO₂One or a combination of two or more of the particles; the D50 particle size of the SiO2 particle is 20nm-80nm, preferably 40nm-50 nm.

As another specific scheme, the weight portion of the aluminum isopropoxide is 10-50%.

The invention has the following beneficial effects:

the hollow nano aluminum fluoride ball has the advantages that the hollow nano aluminum fluoride ball is higher in specific surface area by designing parameters such as the ratio of the inner diameter to the outer diameter, the thickness of the ball wall and the like, and the catalytic efficiency of the hollow nano aluminum fluoride ball material for synthesizing the fluorine-containing organic compound can be further improved in a controllable manner by utilizing the characteristics of the active center, the limited pore space, the adjustable mass transfer rate and the like of the hollow nano aluminum fluoride ball; the BET specific surface area of the hollow nano aluminum fluoride ball related by the invention exceeds 1200m²The inner diameter of the hollow nano aluminum fluoride ball is 20nm-80nm, the wall thickness is 30nm-60nm, namely the inner diameter ratio and the outer diameter ratio are 3: 8-5: and 7, the catalyst has better catalytic efficiency for synthesizing the fluorine-containing organic compound, which is 3-7 times of that of the traditional hollow nano aluminum fluoride ball.

The preparation method of the hollow nano aluminum fluoride ball adopts a hard template method to prepare the hollow nano aluminum fluoride ball, and specifically comprises the steps of preparing an aluminum oxide film on a hard template through a sol-gel method, coating a carbon film, fluoridizing the aluminum oxide film through HF acid (hydrofluoric acid), etching the hard template, and removing the carbon film at high temperature to finally prepare the hollow nano aluminum fluoride ball with controllable inner diameter and outer diameter.

Drawings

Fig. 1 is a flow chart of the preparation of hollow nano aluminum fluoride spheres in one embodiment of the present invention.

Fig. 2 is a diagram of catalytic activity of hollow nano-aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

Fig. 3 is a BET specific surface area chart of hollow nano aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

Fig. 4 is a diagram of the specific surface area of micropores of hollow nano aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

FIG. 5 is a graph of the average pore diameter of hollow nano-aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

Fig. 6 is a total pore volume chart of hollow nano aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

Fig. 7 is a graph of the specific surface area of external pores of hollow nano aluminum fluoride spheres prepared under different conditions according to an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples.

The inner diameter of the hollow nanometer aluminum fluoride ball 4 related to the embodiment is 20nm-80nm, the wall thickness is 30nm-60nm, and the hollow nanometer aluminum fluoride ball 4 has the best catalytic efficiency for synthesizing fluorine-containing organic compounds under the inner diameter and wall thickness ranges.

Further, the inner diameter of the hollow nano aluminum fluoride ball is preferably 40-50nm, and the wall thickness is preferably 40-50 nm.

Further, the ratio of the inner diameter to the outer diameter of the hollow nano aluminum fluoride ball is preferably 4: 9-5: 9.

further, the BET specific surface area of the hollow nano aluminum fluoride ball is larger than or equal to 1200m²/g。

The hollow nano aluminum fluoride ball 4 is prepared by adopting a hard template method, wherein the used hard template 1 preferably selects SiO with uniform surface deposition effect₂Particles;

referring to fig. 1, the preparation method according to the present embodiment includes the following steps:

step one, adding aluminum isopropoxide (the chemical formula of the aluminum isopropoxide is Al (O-i-Pr)) into 100 wt% of ethanol₃Wherein i-Pr represents isopropyl (-CH (CH)₃)₂) Stirring to form a homogeneous solution;

secondly, SiO with the weight percentage of 30 percent₂Adding the granules (powder) into the uniform solution prepared in the step one, continuously stirring and slightly heating to ensure that the ethanol is completely volatilized to form dry powder, and enabling SiO to be completely evaporated₂A uniform layer of Al (OC) is formed on the surface of the particles₃H₇）₃A film;

step three, exposing the dry powder prepared in the step two in the air, and after the dry powder absorbs the moisture in the air, performing hydrolytic polycondensation to form (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃A gel film;

step four, adding (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Placing the gel film in a muffle furnace, heating to 550 deg.C at 3 deg.C/min, and performing heat treatment for 12 hr to obtain (O-H)₇C₃）₃Al-O-Al-（C₃H₇O）₃Conversion of gel film to amorphous Al₂O₃A membrane 2;

step five, adopting a fluorine-containing carbon source to react Al₂O₃Coating with film 2 on Al₂O₃Forming a carbon film 3 on the surface of the film 2, gradually heating to 900-1100 ℃ in a protective atmosphere, and carbonizing for 2h, wherein fluorine (F) ions in the carbonizing process act on Al₂O₃The surface of the film 2 is modified, and simultaneously, the high-temperature atmosphere enables amorphous Al₂O₃Film 2 converted to alpha crystalline Al₂O₃Film 2 (. alpha. -Al)₂O₃) (ii) a Al compared to a fluorine-free carbon source₂O₃Membrane 2 shows a more intense catalytic capacity;

step six, adding HF acid to alpha crystalline Al₂O₃Fluorination of the membrane 2 to obtain a crystalline-like AlF₃Film (aluminum fluoride film), HF acid etching SiO simultaneously₂The particles are treated by a carbon film removing film 3 to prepare hollow nano aluminum fluoride balls 4 with controllable inner and outer diameters; through the catalysis of hydrofluorocarbon, the catalyst is compared with the traditional AlF₃The catalytic effect of the membrane (aluminum fluoride membrane) and the hollow nano aluminum fluoride ball 4 is improved to 3-7 times of that of the traditional membrane.

Further, the hard template 1 may be polystyrene latex particles, colloidal sol and carbon particles, and SiO₂One or a combination of two or more of the particles; SiO is preferred in this embodiment₂The particles act as a hard template 1.

Further, the particle size of the SiO2 particles determines the inner diameter of the hollow nano aluminum fluoride ball 4; based on the preparation method of the hollow nano aluminum fluoride ball 4, the D50 particle size of the SiO2 particle is 20nm-80nm, and specifically 20nm, 30nm, 40nm, 50nm, 60nm and 80nm can be selected.

Further, the weight portion of the aluminum isopropoxide is 10-30%;

the preparation method based on the hollow nano aluminum fluoride ball 4 comprises the following steps:

firstly, 10 percent of aluminum isopropoxide by weight can correspondingly prepare hollow nano aluminum fluoride balls 4 with the wall thickness of 10nm,

② the hollow nanometer aluminum fluoride ball 4 with the wall thickness of 20nm can be correspondingly prepared by 12 percent of aluminum isopropoxide by weight,

③ 15 percent of aluminum isopropoxide by weight is corresponding to the hollow nanometer aluminum fluoride ball 4 with the wall thickness of 30nm,

18 percent of aluminum isopropoxide by weight can correspondingly prepare hollow nano aluminum fluoride balls 4 with the wall thickness of 40nm,

20 percent of aluminum isopropoxide by weight is correspondingly used for preparing the hollow nano aluminum fluoride ball 4 with the wall thickness of 50nm,

sixthly, the hollow nano aluminum fluoride ball 4 with the wall thickness of 60nm can be prepared by using 26 weight percent of aluminum isopropoxide,

and (c) 30 wt% of aluminum isopropoxide corresponds to the hollow nano aluminum fluoride ball 4 with the wall thickness of 70 nm.

The catalytic activity of the hollow nano aluminum fluoride ball 4 prepared under different conditions can be seen in the attached figure 2; according to the attached figure 2, when the hard template 1 adopts SiO2 particles (the inner diameter of the prepared hollow nano aluminum fluoride ball 4 is 50nm correspondingly) with the D50 particle size of 50nm and forms the hollow nano aluminum fluoride ball 4 with the wall thickness of 40nm or 50nm, the inner diameter-to-outer diameter ratio is 5:9 or 1:2, the catalytic activity of the hollow nano aluminum fluoride ball 4 can reach 139.5, the catalytic effect is optimal, and the catalytic effect can reach 6-7 times of that of the traditional method. Further, when the inner diameter was 40nm and the wall thickness was 40nm, or when the inner diameter was 40nm and the wall thickness was 50nm, or when the inner diameter was 60nm and the wall thickness was 50nm, the catalytic activity exceeded 130. It can be seen that by designing the inner-outer diameter ratio, the wall thickness and other parameters of the hollow nano aluminum fluoride ball 4, a higher specific surface area can be obtained, and by utilizing the characteristics of the active center, the limited pore space, the adjustable mass transfer rate and the like of the hollow nano aluminum fluoride ball 4, the catalytic efficiency of the hollow nano aluminum fluoride ball 4 for synthesizing the fluorine-containing organic compound can be further improved in a controllable manner.

The BET specific surface area of the hollow nano aluminum fluoride ball 4 prepared under different conditions can be seen in figure 3.

The specific surface area of the micropores of the hollow nano aluminum fluoride spheres 4 prepared under different conditions can be seen in figure 4.

The average pore diameter of the hollow nano aluminum fluoride ball 4 prepared under different conditions can be seen in figure 5.

The total pore volume of the hollow nano aluminum fluoride ball 4 prepared under different conditions can be seen in figure 6.

The specific surface area of the external hole of the hollow nano aluminum fluoride ball 4 prepared under different conditions can be seen in figure 7.

The foregoing is a preferred embodiment of the present invention, and the basic principles, principal features and advantages of the invention are shown and described. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are intended to illustrate the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and the invention is intended to be protected by the following claims. The scope of the invention is defined by the appended claims and equivalents thereof.