CN112707421A

CN112707421A - Gamma-alumina octahedral crystal grain material and preparation method thereof

Info

Publication number: CN112707421A
Application number: CN201911020741.5A
Authority: CN
Inventors: 王诗语; 杨卫亚; 凌凤香; 张会成; 王少军; 沈智奇
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2019-10-25
Filing date: 2019-10-25
Publication date: 2021-04-27
Anticipated expiration: 2039-10-25
Also published as: CN112707421B

Abstract

The invention discloses a gamma-alumina octahedral crystal grain material, which has a prism shape of a single crystal structure, wherein the distribution proportion of (110) crystal faces is 1-15%, the distribution proportion of (111) crystal faces is 60-85%, and the distribution proportion of (100) crystal faces is 1-25% on the basis of the total exposed crystal face area of an alumina material. The preparation method comprises the following steps: (1) roasting the alumina precursor powder, doping inorganic sodium salt, grinding the powder, washing with water to remove sodium salt, drying, preparing a suspension with a certain concentration, adding an organic acid, and uniformly mixing; (2) adding organic amine and low-carbon alcohol into the material obtained in the step (1) and uniformly stirring; (3) and (3) carrying out closed hydrothermal treatment on the materials, carrying out solid-liquid separation after the treatment is finished, drying and roasting to obtain a product. The gamma-alumina octahedral crystal grain has unique crystal face distribution characteristic, simple preparation process, low cost and excellent application foreground in preparing distillate oil hydrorefining catalyst.

Description

Gamma-alumina octahedral crystal grain material and preparation method thereof

Technical Field

The invention belongs to the field of inorganic material preparation, and particularly relates to a gamma-alumina octahedral crystal grain material and a preparation method thereof.

Background

Activated alumina, as a carrier material widely used in the industrial field, generally has the advantages of high pore volume, high specific surface area, high catalytic activity, and the like. In the heterogeneous catalysis process, key factors influencing the reaction activity and selectivity of the catalyst comprise the properties of the surface and the like of the catalyst. The surface property of the crystal catalyst is closely related to the crystal face of the crystal, the anisotropy of the crystal causes the physicochemical properties of the crystal on different crystal faces to be different, and the catalytic performance of the catalyst has stronger correlation with the exposed crystal face.

For activated alumina (gamma-alumina), research has shown that the (110) crystal plane is thermodynamically most stable and therefore is usually preferentially exposed. Other crystal faces of the activated alumina, such as (111) face and (100) face, have different interface chemical properties from (110) face, and in order to obtain an alumina carrier material with higher performance, the crystal face of the alumina can be regulated and modified by a series of means to obtain special physicochemical properties. But the intrinsic crystal growth habit of the predominance of the (110) crystal plane of activated alumina is difficult to change easily.

[ fine petrochemical, 2014, 31 (5): 38-43, the relation between the surface properties and the crystal plane characteristics of the single crystal small particle gamma-alumina is studied, and the alumina crystal is found to mainly expose (110) crystal plane family and (111) crystal plane family, wherein the surface of the (110) crystal plane family accounts for 70.4 percent, and the surface of the (111) crystal plane family accounts for 29.6 percent.

[ contemporary chemical industry, 2015, 44 (5): 951-954 ] nanometer gamma-alumina single crystal particles containing a (110) crystal plane and further having high-index surface crystal planes (752), (541) and the like are prepared. However, the high-index crystal face of alumina has high activity and large interface energy, is difficult to exist stably in thermodynamics, and is not suitable for being used as a catalytic material in the field of catalytic reaction.

[ petroleum refining and chemical engineering, 2013, 44 (9): 47-50. the crystal face distribution range of the alumina single crystal particles can be changed to a certain extent by adding sodium nitrate into a hydrothermal system, but the regulation range is limited due to the inherent habit of alumina crystals, and the crystal face of alumina is still dominated by (110).

The research results show that the space for directly regulating and controlling the crystal face distribution of the alumina single crystal particles is very limited, and the effect is not very obvious. Other indirect methods of modulating the crystal plane of alumina that may exist are self-assembly. CN200910011627.6, CN200910206229.X and CN200910011626.1 adopt aluminum hydroxide gel prepared by a molten salt super-solubilization micelle self-assembly method as a raw material, and after roasting, regular rod-shaped nano aluminum oxide secondary particles are obtained. [ Chinese science, 2009, 39 (5): 420-431 and [ journal of inorganic chemistry, 2015, 31 (8): 1539-1547, the self-assembly technique and mechanism of the alumina super-solubilization micelle are provided. The self-assembly method of the activated alumina secondary particles can greatly influence the pore structure and the aggregation form of the material, but the obvious effect on the regulation and control of the crystal face distribution and the exposure characteristic of the activated alumina is still difficult to obtain.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a gamma-alumina octahedral crystal grain material and a preparation method thereof.

The gamma-alumina octahedral crystal grain material has the following properties: the material is of a single crystal structure, the shape of the material is a hexagonal prism, the upper hexagonal bottom surface and the lower hexagonal bottom surface are (110) crystal faces, the rectangular side surfaces of the prism are respectively a (111) crystal face and a (100) crystal face, the total area of the exposed crystal faces of the alumina material is taken as a reference, the distribution proportion of the (110) crystal faces is 1% -15%, preferably 5% -10%, the distribution proportion of the (111) crystal faces is 60% -85%, preferably 70% -80%, and the distribution proportion of the (100) crystal faces is 1% -25%, preferably 10% -15%; the length of the alumina material along the [110] crystal axis direction is 100-5000 nm.

The preparation method of the gamma-alumina octahedral crystal grain material comprises the following steps:

(1) roasting the alumina precursor powder, adding a certain amount of inorganic sodium salt, grinding the powder, washing the ground powder with water to remove the sodium salt, drying, preparing a suspension with a certain concentration, adding a certain amount of organic acid, and uniformly mixing;

(2) adding a certain amount of organic amine and low-carbon alcohol into the material obtained in the step (1) and uniformly stirring;

(3) and (3) carrying out closed hydrothermal treatment on the material obtained in the step (2), and after the treatment is finished, carrying out solid-liquid separation, drying and roasting to obtain a product.

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 of the present invention, the calcination temperature in step (1) is 650-.

In the method of the present invention, the material in step (1) is processed by grinding (e.g. ball milling) to obtain a powder particle size of 50 mesh or more, preferably 100-2000 mesh.

In the method, the inorganic sodium salt in the step (1) is one or more of sodium nitrate, sodium chloride or sodium sulfate, and the using amount of the inorganic sodium salt accounts for 0.1-10% of the mass of the calcined alumina precursor powder.

In the method of the present invention, the concentration of the suspension of step (1) is 1 to 100g/L, preferably 10 to 50g/L

In the method, the organic acid in the step (1) is one or more of formic acid, acetic acid or citric acid, and the using amount of the organic acid is 0.1-8% of the mass of the calcined alumina precursor, and is preferably 0.5-5%.

In the method of the invention, the organic amine in the step (2) is one or more of aniline, diphenylamine, benzidine or o-phenylenediamine. The concentration of the organic amine in the material system is 1-200g/L, preferably 10-100 g/L.

In the method of the present invention, the lower alcohol in step (2) is one or more of methanol, ethanol or propanol, preferably methanol and/or ethanol. The concentration of the lower alcohol in the material system is 1-40g/L, preferably 10-30 g/L.

In the method, the closed hydrothermal conditions in the step (3) are as follows: hydrothermal treatment at 100 ℃ and 300 ℃ for 0.5-24 hours, preferably at 150 ℃ and 250 ℃ for 2-12 hours.

In the method of the present invention, the drying temperature in the step (3) is not more than 200 ℃, preferably not more than 120 ℃, and the drying degree is that the material reaches a constant weight at the drying temperature.

In the method, the roasting conditions in the step (3) are as follows: roasting at 750 ℃ for 1-24 hours at 450-.

The invention also provides a distillate oil hydrofining catalyst, which comprises the gamma-alumina octahedral crystal grain material.

The gamma-alumina octahedral crystal grain material has unique crystal face distribution characteristic, simple preparation process, low cost and excellent application foreground in fraction oil hydrorefining field.

Drawings

Fig. 1 is a scanning electron micrograph of the gamma-alumina material prepared in example 1.

FIG. 2 is an electron diffraction spectrum in the [110] direction of the gamma-alumina material prepared in example 1.

Fig. 3 is an XRD spectrum of the gamma-alumina material prepared in example 1.

Detailed Description

The process of the present invention is illustrated in detail by the following examples. The grain size of the gamma-alumina material was measured according to scanning electron microscope images. Randomly measuring 20 particles, and taking the average axial length value as the height value of the particles; the crystal form is characterized by X-ray diffraction; collecting an electron diffraction spectrum through a transmission electron microscope, and processing a sample through a slicing means before carrying out electron diffraction analysis on a large-particle sample.

Example 1

Calcining 10g of pseudo-boehmite powder at 700 ℃ for 5 hours, adding 0.5 g of sodium chloride, uniformly mixing, grinding into micropowder by using a ball mill, sieving to obtain particles with about 500 meshes, washing with distilled water to remove the sodium chloride, and preparing 20g/L aqueous suspension. Adding acetic acid into the suspension, wherein the dosage of the acetic acid is 0.5 percent of the mass of the calcined alumina precursor. Adding diphenylamine and ethanol into the system, wherein the mass percentage concentration of diphenylamine and ethanol is 10g/L and 10g/L respectively, uniformly stirring, sealing the system, and heating to 150 ℃ for hydrothermal treatment for 12 hours. And roasting the product dried at the temperature of 120 ℃ for 4 hours at the temperature of 650 ℃ to obtain the product. The observation of a scanning electron microscope shows that the appearance of the product is approximately regular hexagonal prism. The XRD result of the product shows that the phase state is gamma phase. According to the electron diffraction analysis of the cross section, the orientation is [110] along the column height direction, the bottom surface is a (110) crystal plane (in a hexagon shape), and the side surfaces of the hexagonal prism are respectively a (100) plane and a (111) plane according to the included angle relationship. The electron diffraction of the material is orderly arranged spots, so that the material is known to have a single crystal structure. Wherein, 2 (110) surfaces, 2 (100) surfaces and 4 (111) surfaces are provided. The length along the [110] direction is 1080nm, the average size of (100) crystal planes is 125nm 1080nm, and the average size of (111) crystal planes is 248 nm 1080 nm. The calculation shows that the proportion of the (110) crystal face is 9 percent, the proportion of the (111) crystal face is 67 percent, and the proportion of the (100) crystal face is 24 percent.

Example 2

10g of pseudo-boehmite powder is roasted for 2 hours at 800 ℃, 0.5 g of sodium nitrate is added and mixed evenly, the mixture is ground into micro powder by a ball mill, particles about 1000 meshes are sieved, the sodium nitrate is removed by washing with distilled water, and then 15g/L of aqueous suspension is prepared. Adding acetic acid into the suspension, wherein the dosage of the acetic acid is 0.3 percent of the mass of the pseudo-boehmite powder. Adding diphenylamine and propanol into the system, wherein the mass percentage concentration of the diphenylamine and the propanol is 10g/L and 25g/L respectively, uniformly stirring, sealing the system, and heating to 200 ℃ for hydrothermal treatment for 12 hours. And roasting the product dried at the temperature of 120 ℃ for 4 hours at the temperature of 650 ℃ to obtain the product. The observation of a scanning electron microscope shows that the appearance of the product is approximately regular hexagonal prism. The XRD result of the product shows that the phase state is gamma phase. According to the electron diffraction analysis of the cross section, the orientation is [110] along the column height direction, the bottom surface is a (110) crystal plane (in a hexagon shape), and the side surfaces of the hexagonal prism are respectively a (100) plane and a (111) plane according to the included angle relationship. The electron diffraction of the material is orderly arranged spots, so that the material is known to have a single crystal structure. Wherein, 2 (110) surfaces, 2 (100) surfaces and 4 (111) surfaces are provided. The length along the (110) direction was 2032nm, the average size of (100) planes was 85nm 2032nm, and the average size of (111) planes was 184 nm 2032 nm. The calculation revealed that the proportion of (110) plane was 7%, the proportion of (111) plane was 76%, and the proportion of (100) plane was 17%.

Example 3

10g of pseudo-boehmite powder is roasted for 7 hours at 650 ℃, 0.8 g of sodium nitrate is added and mixed evenly, the mixture is ground into micro powder by a ball mill, particles about 2000 meshes are sieved, distilled water is used for washing to remove the sodium nitrate, and then 35g/L of aqueous suspension is prepared. Adding part of acetic acid into the suspension, wherein the dosage of the acetic acid is 1.5 percent of the mass of the pseudo-boehmite powder. The treatment was carried out at room temperature for 15 minutes. And (3) adding benzidine and methanol into the system, wherein the mass percentage concentration of the benzidine and the methanol is 5g/L and 25g/L respectively, uniformly stirring, sealing the system, and heating to 200 ℃ for hydrothermal treatment for 7 hours. And roasting the product dried at the temperature of 120 ℃ for 4 hours at the temperature of 650 ℃ to obtain the product. The observation of a scanning electron microscope shows that the appearance of the product is approximately regular hexagonal prism. The XRD result of the product shows that the phase state is gamma phase. According to the electron diffraction analysis of the cross section, the orientation is [110] along the column height direction, the bottom surface is a (110) crystal plane (in a hexagon shape), and the side surfaces of the hexagonal prism are respectively a (100) plane and a (111) plane according to the included angle relationship. The electron diffraction of the material is orderly arranged spots, so that the material is known to have a single crystal structure. Wherein, 2 (110) surfaces, 2 (100) surfaces and 4 (111) surfaces are provided. The length along the [110] direction was 345nm, the average size of (100) planes was 56nm 345nm, and the average size of (111) planes was 79 nm 345 nm. The calculation shows that the proportion of (110) plane is 12.5%, the proportion of (111) plane is 64.7% and the proportion of (100) plane is 22.8%.

Comparative example 1

Reference [ petroleum refining and chemical, 2013, 44 (9): 47-50 ] adjusting the crystal plane distribution of the alumina single crystal particles by adding sodium nitrate. The test conditions are shown in the literature. The two groups were divided, the first group without sodium nitrate and the second group with sodium nitrate. The product contains (110), (111) and (100) crystal faces with low index. The first set of three crystal planes is distributed: (110) % is 72.3%, (111)% is 20.5%, (100)% is 7.2%; the second set of three crystal planes are: (110) % is 64.2%, (111)% is 26.4%, and (100)% is 9.4%. It can be seen that the distribution of the (110) crystal planes is still dominant, whether or not sodium nitrate is added, and is greater than 50%.

Comparative example 2

According to [ chinese science, 2009, 39 (5): 420-431 ] the fused salt supersolubility micelle self-assembly method is used for preparing the alumina self-assembly particles. The results obtained were tested and found that the self-assembly as a whole has no significant orientation of the crystal planes and that the individual grains remain the (110) -dominated distribution of crystal planes.

Claims

1. A gamma-alumina octahedral crystal grain material is characterized by the following properties: the material is of a single crystal structure, the shape of the material is a hexagonal prism, the upper hexagonal bottom surface and the lower hexagonal bottom surface are (110) crystal faces, the rectangular side surfaces of the prism are respectively (111) crystal faces and (100) crystal faces, and the total area of the exposed crystal faces of the aluminum oxide material is taken as a reference, the distribution ratio of the (110) crystal faces is 1% -15%, the distribution ratio of the (111) crystal faces is 60% -85%, and the distribution ratio of the (100) crystal faces is 1% -25%.

2. The crystalline material of claim 1, characterized in that: based on the total exposed crystal face area of the aluminum oxide material, the distribution ratio of (110) crystal faces is 5-10%, the distribution ratio of (111) crystal faces is 70-80%, and the distribution ratio of (100) crystal faces is 10-15%.

3. The crystalline material of claim 1, characterized in that: along the [110] crystal axis direction, the length of the gamma-alumina octahedral crystal grain material is 100-5000 nm.

4. A method for preparing the gamma-alumina octahedral crystal grain material according to any one of claims 1 to 3, characterized by comprising the following steps: (1) roasting the alumina precursor powder, adding a certain amount of inorganic sodium salt, grinding the powder, washing the ground powder with water to remove the sodium salt, drying, preparing a suspension with a certain concentration, adding a certain amount of organic acid, and uniformly mixing; (2) adding a certain amount of organic amine and low-carbon alcohol into the material obtained in the step (1) and uniformly stirring; (3) and (3) carrying out closed hydrothermal treatment on the material obtained in the step (2), and after the treatment is finished, carrying out solid-liquid separation, drying and roasting to obtain a product.

5. The method of claim 4, wherein: the alumina precursor in the step (1) is pseudo-boehmite or pseudo-boehmite modified by silicon, boron, titanium, magnesium or lanthanum.

6. The method of claim 4, wherein: the roasting temperature in the step (1) is 650-900 ℃, and the roasting time is 1-24 hours.

7. The method of claim 4, wherein: the material in the step (1) is ground to obtain powder with the granularity of more than 50 meshes, and the powder granularity is preferably 100-2000 meshes.

8. The method of claim 4, wherein: the inorganic sodium salt in the step (1) is one or more of sodium nitrate, sodium chloride or sodium sulfate, and the using amount of the inorganic sodium salt accounts for 0.1-10% of the mass of the calcined alumina precursor powder.

9. The method of claim 4, wherein: the concentration of the suspension liquid in the step (1) is 1-100 g/L.

10. The method of claim 4, wherein: the organic acid in the step (1) is one or more of formic acid, acetic acid or citric acid; the dosage of the alumina precursor is 0.1-8% of the mass of the calcined alumina precursor.

11. The method of claim 4, wherein: the organic amine in the step (2) is one or more of aniline, diphenylamine, benzidine or o-phenylenediamine; the concentration of the organic amine in the material system is 1 g/L-200 g/L.

12. The method of claim 4, wherein: the lower alcohol in the step (2) is one or more of methanol, ethanol or propanol; the concentration of the low-carbon alcohol in the material system is 1 g/L-40 g/L.

13. The method of claim 4, wherein: the closed hydrothermal condition of the step (3) is as follows: hydrothermal treatment at 100-300 deg.c for 0.5-24 hr.

14. The method of claim 4, wherein: the roasting conditions in the step (3) are as follows: roasting at 450-750 deg.c for 1-24 hr.

15. A distillate oil hydrofining catalyst is characterized in that: the catalyst comprises a gamma-alumina octahedral crystalline grain material according to any of claims 1 to 3.

16. Use of a gamma-alumina octahedral crystalline grain material according to any one of claims 1 to 3 in a distillate hydrogenation process.