阅读说明：本技术 一种多晶氧化铝自组装八面体颗粒的制备方法 (Preparation method of self-assembled octahedral particles of polycrystalline alumina ) 是由 张雁玲 杨卫亚 凌凤香 张会成 王少军 沈智奇 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种多晶氧化铝自组装八面体颗粒的制备方法,包括如下内容：(1)将焙烧后的氧化铝前驱体粉体以等体积浸渍法使其充分吸附有机胺溶液,然后使用高能球磨机处理粉体；(2)将步骤(1)得到的物料干燥,筛取合适粒度的物料；(3)将步骤(2)筛取的物料进行密闭水热处理；密闭体系中,分为上下两部分：上部分为氧化铝前体固态物料,下部分为液相,固液两相不直接接触,在高温下发生气-固反应,反应结束后,经干燥、焙烧得到产物。本发明方法简单、绿色环保,本发明方法合成的氧化铝材料在催化、吸附领域有着广阔的应用前景。(The invention discloses a preparation method of self-assembled octahedral particles of polycrystalline alumina, which comprises the following steps: (1) fully adsorbing the organic amine solution by the calcined alumina precursor powder by an isometric impregnation method, and then treating the powder by using a high-energy ball mill; (2) drying the material obtained in the step (1), and screening the material with proper granularity; (3) carrying out closed hydrothermal treatment on the material screened in the step (2); in the closed system, the device is divided into an upper part and a lower part: the upper part is an alumina precursor solid material, the lower part is a liquid phase, the solid phase and the liquid phase are not directly contacted, gas-solid reaction is carried out at high temperature, and after the reaction is finished, the product is obtained by drying and roasting. The method is simple and environment-friendly, and the aluminum oxide material synthesized by the method has wide application prospects in the fields of catalysis and adsorption.)

1. A preparation method of self-assembled octahedral particles of polycrystalline alumina is characterized by comprising the following steps: (1) fully adsorbing the organic amine solution by the calcined alumina precursor powder by an isometric impregnation method, and then treating the powder by using a high-energy ball mill; (2) drying the material obtained in the step (1), and screening the material with proper granularity; (3) carrying out closed hydrothermal treatment on the material screened in the step (2); in the closed system, the device is divided into an upper part and a lower part: the upper part is solid material, the lower part is organic amine water solution, the solid phase and the liquid phase are not directly contacted, gas-solid reaction is carried out at high temperature, and after the reaction is finished, the solid phase is dried and roasted to obtain the product.

2. The method of claim 1, wherein: the alumina precursor in the step (1) is pseudo-boehmite or a silicon, boron, titanium, magnesium and lanthanum modified pseudo-boehmite powder.

3. The method of claim 1, wherein: the roasting conditions of the alumina precursor in the step (1) are as follows: the roasting temperature is 250 ℃ and 450 ℃, and the roasting time is 1-12 hours.

4. The method of claim 1, wherein: the high-energy ball mill in the step (1) is used for processing to obtain powder granularity of 5000-20000 meshes.

5. The method of claim 1, wherein: the organic amine in the step (1) is one or more of ethanolamine, diethanolamine, triethanolamine, aniline, diphenylamine, benzidine or o-phenylenediamine.

6. The method of claim 1, wherein: the adsorption amount of the organic amine in the step (1) is 1-20% of the mass of the calcined alumina precursor, and is preferably 5-15%.

7. The method of claim 1, wherein: the drying conditions in the step (2) are as follows: the drying temperature is 60-120 ℃, and the drying time is 2-24 hours.

8. The method according to claim 1, characterized in that: the closed hydrothermal condition of the step (3) is as follows: hydrothermal treatment at 100-250 deg.c for 12-96 hr.

9. The method of claim 1, wherein: the concentration of the organic amine aqueous solution at the middle lower part of the step (3) is 1-300 g/L, preferably 50-200 g/L.

10. An alumina self-assembly particle prepared by the method of any one of claims 1 to 9, characterized in that: the octahedron has a hexagonal prism-shaped octahedron stereo morphology, 8 surfaces outside the particles are divided into 4 groups, every two surfaces of each group are opposite and parallel or approximately parallel, the 4 groups of surfaces are intersected and sealed to form the octahedron, and the ratio of the height of a prism to the longest diagonal of the cross section of the prism is 2-15.

Technical Field

The invention belongs to the field of inorganic material preparation, and particularly relates to a preparation method of self-assembled octahedral particles of polycrystalline alumina.

Background

Alumina is a widely used catalyst support material, and crystal faces exposed by surface properties of the alumina are directly related and have important influence on the performance of the catalyst. For gamma-alumina, the (110) lattice plane is thermodynamically most stable and is usually preferentially exposed. The (111) crystal face and the (100) crystal face of the aluminum oxide have different atomic arrangement and chemical properties from the (110) crystal face, so that special interface properties can be obtained by regulating the crystal face of the aluminum oxide. However, the situation in which the aluminum oxide (110) crystal face predominates is hardly easily changed as a whole.

The existing research shows that the single crystal alumina crystal grains mainly expose { 110 } crystal face family and { 111 } crystal face family, the { 110 } crystal face family accounts for 70.4%, and the { 111 } crystal face family accounts for 29.6%. The crystal plane distribution ratio of alumina crystal grains is difficult to regulate due to the intrinsic constraint mechanism of crystal habit, and the { 110 } crystal plane family is always in a dominant position.

[ petroleum refining and chemical engineering, 2013, 44 (9): 47-50 ] regulating and controlling the crystal face distribution of the aluminum oxide single crystal by introducing sodium nitrate, wherein the obtained crystal grains are still mainly the (110) crystal face.

CN200910011627.6, cn200910206229.x and CN200910011626.1 synthesized rod-shaped alumina assembly particles by a supersolubilization micelle method. The self-assembly method has no obvious effect on the distribution ratio of the oxidation crystal face.

[ chemical bulletin of fuel, 2013, 41 (10): 1262-1267 aluminum chloride is used as precursor, hexagonal prism shaped polycrystal gamma-alumina polycrystal particles are prepared by a hydrothermal method in an ammonia water medium, and the obtained product contains a large amount of chlorine element, and needs to be removed by a special means, which is not beneficial to green utilization in industry.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of self-assembled octahedral particles of polycrystalline alumina, the invention uses organic amine of a specific type as a self-assembly regulating agent to enable an alumina precursor to generate self-assembly action under a certain chemical environment to form an octahedral morphology structure, and the method is simple, green and environment-friendly.

The preparation method of the polycrystalline alumina self-assembled octahedral particles comprises the following steps:

(1) fully adsorbing the organic amine solution by the calcined alumina precursor powder by an isometric impregnation method, and then treating the powder by using a high-energy ball mill;

(2) drying the material obtained in the step (1), and screening the material with proper granularity;

(3) carrying out closed hydrothermal treatment on the material screened in the step (2); in the closed system, the device is divided into an upper part and a lower part: the upper part is solid material, the lower part is organic amine water solution, the solid phase and the liquid phase are not directly contacted, gas-solid reaction is carried out at high temperature, and after the reaction is finished, the product is obtained by drying and roasting.

In the method of the present invention, the alumina precursor in step (1) refers to pseudo-boehmite and pseudo-boehmite powder modified by various elements such as silicon, boron, titanium, magnesium, lanthanum, etc.

In the method, the roasting conditions of the alumina precursor in the step (1) are as follows: roasting at 250-450 ℃ for 1-12 hours; the preferred firing conditions are: baking at 300-450 deg.C for 2-8 hr.

In the method, the high-energy ball milling treatment in the step (1) is carried out to obtain powder granularity of 5000-. The operating conditions of the high-energy ball mill are flexibly adjusted by taking the powder granularity meeting the requirements as a standard.

In the method, the organic amine in the step (1) is one or more of ethanolamine, diethanolamine, triethanolamine, aniline, diphenylamine, benzidine or o-phenylenediamine. The adsorption capacity of the organic amine is 1-20% of the calcined mass of the alumina precursor, and preferably 5-15%. The concentration of the organic amine solution can be reasonably adjusted according to specific adsorption conditions, and the solvent of the organic amine solution can be water and/or low-carbon alcohol.

In the method, the drying condition in the step (2) is 60-120 ℃, and the drying time is 2-24 hours.

In the method, the closed hydrothermal conditions in the step (3) are as follows: hydrothermal treatment is carried out for 12 to 96 hours at the temperature of between 100 and 250 ℃, and the hydrothermal time is preferably 24 to 72 hours.

In the method of the present invention, the concentration of the aqueous organic amine solution in the lower part of step (3) is 1 to 300 g/L, preferably 50 to 200 g/L.

In the method, the drying temperature in the step (3) is not more than 200 ℃, preferably not more than 120 ℃, and the drying degree is the constant weight of the material at the drying temperature. The roasting conditions are as follows: baking at 500-700 ℃ for 1-24 hours.

The alumina self-assembly particles prepared by the method have a hexagonal prism-shaped octahedron stereo morphology, 8 surfaces outside the particles are divided into 4 groups, every two surfaces of each group are opposite and parallel or approximately parallel, the 4 groups of surfaces are intersected and sealed to form an octahedron, and the ratio of the height of a prism to the longest diagonal line of the cross section of the prism is 2-15. The material has wide application prospect in the fields of adsorption and catalysis.

Drawings

FIG. 1 is a scanning electron micrograph of octahedral alumina particles prepared in example 1.

FIG. 2 is an electron diffraction spectrum of the octahedral alumina particles prepared in example 1.

Fig. 3 is an XRD spectrum of the octahedral alumina particles prepared in example 1.

Detailed Description

The process of the present invention is illustrated in detail by the following examples. The octahedral alumina particle size is measured according to scanning electron microscope images. Randomly measuring the heights of 20 particles, and taking the average value as the height value of the particles; the small crystal grains constituting the polyhedral particles are observed by a transmission electron microscope to observe the size range of the particles. The crystal form is characterized by X-ray diffraction. Electron diffraction spectra were collected by transmission electron microscopy.

Example 1

15 g of SB powder is roasted and ground into micro powder by a ball mill, powder with about 5000 meshes is selected to prepare aniline solution, and then the aniline solution is adsorbed on the alumina precursor powder by an isovolumetric impregnation method, wherein the dosage of the aniline is 4 percent of the dosage of the roasted alumina precursor. After drying at 120 ℃, the material is placed in a closed system, the lower part of the closed system is 25g/L aniline solution, the upper part of the closed system is the treated alumina precursor, and the solid phase is not directly contacted with the liquid phase.

Heating the closed system to 250 ℃, and carrying out hydrothermal treatment for 24 hours. And naturally cooling to take out the product, drying at 120 ℃, and roasting at 550 ℃ for 4 hours to obtain the product. The observation of a scanning electron microscope shows that the product is hexagonal prism-shaped octahedron particles and has an approximate regular octahedron stereo morphology, 8 surfaces outside the particles are divided into 4 groups, every two surfaces of each group are opposite and parallel or approximately parallel, and the 4 groups of surfaces are intersected and sealed to form the octahedron particles. The XRD result of the product shows that the phase state is gamma phase. The electron diffraction pattern of the sample fragment is annular, indicating a polycrystalline structure. The ratio of the height of the particle column to the diameter of the column (maximum) is about 9.

Example 2

15 g of SB powder is roasted and ground into micro powder by a ball mill, powder with about 10000 meshes is selected to prepare aniline solution, and then the aniline solution is adsorbed on the alumina precursor powder by an isovolumetric impregnation method, wherein the dosage of the aniline is 2.5 percent of the dosage of the roasted alumina precursor. After drying at 120 ℃, the material is placed in a closed system, the lower part of the closed system is 20g/L aniline solution, the upper part of the closed system is the treated alumina precursor, and the solid phase is not directly contacted with the liquid phase.

Heating the closed system to 200 ℃, and carrying out hydrothermal treatment for 36 hours. And naturally cooling to take out the product, drying at 120 ℃, and roasting at 550 ℃ for 4 hours to obtain the product. The observation of a scanning electron microscope shows that the product is hexagonal prism-shaped octahedron particles and has an approximate regular octahedron stereo morphology, 8 surfaces outside the particles are divided into 4 groups, every two surfaces of each group are opposite and parallel or approximately parallel, and the 4 groups of surfaces are intersected and sealed to form the octahedron particles. The XRD result of the product shows that the phase state is gamma phase. The electron diffraction pattern of the sample fragment is annular, indicating a polycrystalline structure. The ratio of the height of the particle column to the diameter of the column (maximum) is about 7.

Example 3

15 g of silicon modified SB powder is roasted and ground into micro powder by a ball mill, powder with about 20000 meshes is selected to prepare ethanolamine solution, and then the ethanolamine solution is adsorbed on alumina precursor powder by an isovolumetric impregnation method, wherein the dosage of aniline is 6 percent of the dosage of the calcined alumina precursor. After drying at 120 ℃, the material is placed in a closed system, the lower part of the closed system is 20g/L aniline solution, the upper part of the closed system is the treated alumina precursor, and the solid phase is not directly contacted with the liquid phase.

Heating the closed system to 200 ℃, and carrying out hydrothermal treatment for 12 hours. And naturally cooling to take out the product, drying at 120 ℃, and roasting at 550 ℃ for 4 hours to obtain the product. The observation of a scanning electron microscope shows that the product is hexagonal prism-shaped octahedron particles and has an approximate regular octahedron stereo morphology, 8 surfaces outside the particles are divided into 4 groups, every two surfaces of each group are opposite and parallel or approximately parallel, and the 4 groups of surfaces are intersected and sealed to form the octahedron particles. The XRD result of the product shows that the phase state is gamma phase. The electron diffraction pattern of the sample fragment is annular, indicating a polycrystalline structure. The ratio of the height of the particle column to the diameter of the column (maximum) is about 12.

Comparative example 1

According to the chemical journal of fuel, 2013, 41 (10): 1262-1267 ] prismatic alumina octahedron is prepared with aluminum chloride as material. The obtained product is tested to contain a large amount of chlorine element, and if the chlorine element is removed, a large amount of acidic water is consumed, so that the environmental pollution is caused. The process of the present invention for producing prismatic alumina uses a starting chlorine content which is present only as an impurity and the resulting product does not require additional dechlorination.