Method for simply and conveniently constructing amorphous hydrated alumina

Abstract

The invention relates to a preparation method of amorphous hydrated alumina, and belongs to the technical field of inorganic materials. According to the method, hydrated alumina is taken as a raw material, and the hydrated alumina is converted into amorphous hydrated alumina by directly destroying a crystal structure in a ball-milling process by regulating and controlling mechanical ball-milling time under the condition of not adding a chemical additive or carrying out solution treatment. The method is easy and convenient to operate, raw materials are common, and the complex steps of sol-gel, hydrothermal reaction, template construction and the like commonly used in traditional amorphous material preparation are remarkably simplified. Through structural characterization, the obtained product has obvious amorphous characteristics, has good structural uniformity and high reaction activity, and is suitable for subsequent synthesis and functional development of various aluminum oxide materials. The process is mild in condition, environment-friendly, easy to realize industrial amplification and good in popularization and application prospect.

Description

Technical Field

[0001] The invention relates to a method for simply constructing amorphous hydrated aluminum oxide. Background Art

[0002] Hydrated alumina has a wide range of raw materials. Due to the presence of crystalline water, it has a structure different from conventional alumina, so it can meet some special functional requirements and has great application prospects. However, the current preparation of amorphous hydrated alumina mostly relies on complex wet chemical methods, such as sol-gel method, coprecipitation method, hydrothermal synthesis, etc. These methods often involve multi-step reactions and strict control of reaction conditions, such as solution pH, temperature, and drop rate, and require long aging, washing, drying and other processes. The operation is cumbersome and the process window is narrow, making it difficult to achieve large-scale and low-cost production. For example, a study (Synthesis and characterization of nanoα-alumina by an inorganic sol–gel method[J].MaterialsScience and Engineering:B.2022,280:115690) synthesized alumina precursors using Al(NO3)3·9H2O), AlCl3·6H2O and NaOH, but it requires multiple steps such as pH control, hydrothermal reaction, drying and decomposition. The precursor construction process is complicated, and the sample is affected by the intermediate NaAl in the subsequent processing process. 11 O 17 In addition, Zhang et al. (Facile Preparation and Promising Hydrothermal Stability of Spherical γ-Alumina Support with High Specific Surface Area [J]. Catalysts. 2022, 12: 11) prepared γ-Al2O3 with a large specific surface area from a precursor by an oil-ammonia column method. However, the process involved multiple heating reactions, oil-ammonia column gelation, and multiple washings. The overall process was complex and time-consuming, making it difficult to achieve a simple and efficient amorphous precursor construction.

[0003] In summary, existing technologies for creating amorphous hydrated alumina suffer from complex methods, poor process stability, and challenges associated with industrial scale-up. Therefore, developing a simple, straightforward, additive-free, and suitable technology for amorphizing hydrated alumina, suitable for conventional powder processing equipment, is of significant research and application value. Summary of the Invention

[0004] The present invention provides a method for simply constructing amorphous hydrated alumina, which directly acts on the hydrated alumina raw material through mechanical ball milling without the need for sol-gel, hydrothermal or ball-forming treatment. The process is simple and efficient, and the obtained precursor has good structural uniformity and reaction activity.

[0005] The specific scheme among the present invention is:

[0006] The preparation of amorphous hydrated aluminum oxide comprises the following steps:

[0007] (1) Weigh a certain amount of different precursor powders, place them in an agate ball mill, place zirconium balls with a certain ball-to-material ratio, and ball mill them in a planetary ball mill at a certain speed for a period of time to obtain powder A;

[0008] (2) Powder A was taken out, placed in an agate mortar, and ground at room temperature for 20 min to obtain powder B.

[0009] Furthermore, in (1), the precursor powder is boehmite, pseudo-boehmite and aluminum hydroxide;

[0010] Furthermore, in (1), the ball-to-material ratio is: 5 / 1-12 / 1;

[0011] Furthermore, in (1), the ball milling time is: 10-48h;

[0012] Furthermore, in (1), the ball mill has a rotation speed of 400-700 r / min.

[0013] This patent proposes a method for preparing amorphous hydrated alumina, which involves placing the precursor raw material into a ball mill and subjecting it to mechanical ball milling for a certain period of time to achieve an amorphous state. The experimental process is simple and convenient, reducing energy consumption and saving resource costs.

[0014] In the present invention, the precursor powder is boehmite, pseudo-boehmite and aluminum hydroxide, more preferably boehmite and pseudo-boehmite, and most preferably boehmite.

[0015] In the present invention, the ball-to-material ratio is 5 / 1-12 / 1, more preferably 8 / 1-11 / 1, and most preferably 10 / 1.

[0016] In the present invention, the ball milling time is 10-48 hours, more preferably 30-48 hours, and most preferably 48 hours.

[0017] In the present invention, the ball mill rotation speed is 400-700 r / min, more preferably 500-600 r / min, and most preferably 600 r / min.

[0018] Based on the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0019] The reagents and raw materials used in the present invention are commercially available.

[0020] The positive progress effect of the present invention is:

[0021] (1) The preparation process of the present invention does not require complicated equipment, is easy to operate, and is suitable for large-scale industrial production.

[0022] (2) The preparation method of the present invention greatly reduces energy consumption and lowers production costs.

[0023] (3) The amorphous precursor prepared by the present invention has the characteristics of uniform structure and high reaction activity, and can be used as an excellent intermediate in the preparation process of various aluminum oxide materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of XRD of amorphous boehmite prepared in Example 1;

[0025] Figure 2 This is a schematic diagram of XRD of amorphous boehmite prepared in Example 2;

[0026] Figure 3 This is a schematic diagram of XRD of amorphous boehmite prepared in Example 3;

[0027] Figure 4 This is a schematic diagram of XRD of amorphous boehmite prepared in Example 4;

[0028] Figure 5 This is a schematic diagram of XRD of amorphous boehmite prepared in Example 5;

[0029] Figure 6 This is a schematic diagram of XRD of amorphous pseudo-boehmite prepared in Comparative Example 1;

[0030] Figure 7 This is a schematic diagram of XRD of amorphous aluminum hydroxide prepared in Comparative Example 2;

[0031] Figure 8 This is the XRD pattern of boehmite raw material;

[0032] Figure 9 This is the XRD pattern of pseudo-boehmite raw material;

[0033] Figure 10 This is the XRD pattern of aluminum hydroxide raw material. DETAILED DESCRIPTION

[0034] The present invention is further illustrated by way of examples below. However, the present invention is not limited to the scope of the examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the present invention are considered equivalent substitutions and are included within the scope of protection of the present invention. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions or selected according to the product specifications.

[0035] Example 1

[0036] (1) An appropriate amount of boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 10:1. The mixture was then placed in a planetary ball mill for ball milling. The ball milling time was set to 48 h and the ball mill speed was set to 600 r / min.

[0037] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0038] The XRD pattern of the amorphous boehmite prepared in this example is as follows: Figure 1 The results show that the sample lacks distinct, sharp diffraction peaks, with a broad overall spectrum. The diffraction peak intensity is particularly weak in the 2θ range of ≈ 20°-40°, indicating that the material has transitioned from a crystalline state to a long-range disordered amorphous structure. This result confirms that mechanical ball milling effectively destroys the boehmite crystal structure and successfully constructs an amorphous alumina precursor.

[0039] Example 2

[0040] (1) An appropriate amount of boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 12:1. The mixture was then placed in a planetary ball mill for ball milling. The ball milling time was set to 45 h and the ball mill speed was set to 550 r / min.

[0041] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0042] The XRD pattern of the amorphous boehmite prepared in this example is as follows: Figure 2 As shown, the sample has multiple broad and weak diffraction peaks in the range of 2θ≈10°-30°, but no typical sharp diffraction peaks are observed in the spectrum, indicating that the sample has not maintained a complete long-range ordered structure. This diffraction behavior indicates that the sample has a rudimentary amorphous structure under ball milling conditions.

[0043] Example 3

[0044] (1) An appropriate amount of boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 8:1. The mixture was then placed in a planetary ball mill for ball milling. The ball milling time was set to 40 h and the ball mill speed was set to 500 r / min.

[0045] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0046] The XRD pattern of the amorphous boehmite prepared in this example is as follows: Figure 3 As shown in the figure, the XRD pattern of this sample has low diffraction intensity and no obvious sharp diffraction peaks, indicating that the crystal structure of the sample has been destroyed and lacks long-range order. The above diffraction characteristics indicate that the ball milling treatment has caused the material to transform from a crystalline state to an amorphous state.

[0047] Example 4

[0048] (1) An appropriate amount of boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 11:1. The mixture was then placed in a planetary ball mill for milling. The milling time was set to 35 h and the speed was set to 500 r / min.

[0049] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0050] The XRD pattern of the amorphous boehmite prepared in this example is as follows: Figure 4 As shown in the figure, the XRD pattern of the sample shows diffraction peaks at the crystal plane indices (020) and (150), but the other overall peaks are relatively broad and the diffraction intensity is relatively low. The above diffraction characteristics indicate that the sample has basically lost its long-range ordered crystal structure and has the typical characteristics of an amorphous material.

[0051] Example 5

[0052] (1) An appropriate amount of boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 10:1. The mixture was then placed in a planetary ball mill for milling. The milling time was set to 30 h and the speed was set to 600 r / min.

[0053] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0054] The XRD pattern of the amorphous boehmite prepared in this example is as follows: Figure 5As shown in the figure, the sample does not show obvious sharp diffraction peaks in the XRD spectrum, and is mainly distributed in the range of 2θ≈10°-40°. The crystal plane information corresponding to the standard card diffraction peaks is marked in the figure, such as (020), (130), (150), and (151). In this sample, only very weak and fuzzy signals exist, indicating that the original crystal structure has been significantly destroyed, further verifying the effective role of the ball milling process in the amorphous construction process.

[0055] Comparative Example 1

[0056] (1) An appropriate amount of pseudo-boehmite raw material (20 g) was weighed on an electronic balance and placed in four equal portions in an agate jar. Zirconium balls were then added at a mass ratio of zirconium balls to powder of 12:1. The mixture was then placed in a planetary ball mill for milling. The milling time was set to 30 h and the speed of the ball mill was set to 600 r / min.

[0057] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0058] The XRD pattern of the pseudo-boehmite prepared in this embodiment is as follows: Figure 6 As shown in the figure, the XRD pattern of this sample shows obvious diffraction peaks corresponding to the crystal plane indices (020), (021), (130), and (150), and some grains still maintain long-range order. This phenomenon suggests that the ball milling time may be too short, the energy input is insufficient, or the ball-to-material ratio is inappropriate, resulting in the pseudo-boehmite failing to achieve the ideal amorphous state.

[0059] Comparative Example 2

[0060] (1) Weigh an appropriate amount of aluminum hydroxide raw material 20g on an electronic balance, divide it into four equal parts and put it into an agate jar, then add zirconium balls with a mass ratio of zirconium balls to powder = 10:1, put it into a planetary ball mill for ball milling, set the ball milling time to 30h, and set the ball mill speed to 500r / min.

[0061] (2) Take out the ball-milled powder and grind it in an agate mortar for 20 minutes.

[0062] The XRD pattern of the amorphous aluminum hydroxide prepared in this embodiment is as follows: Figure 7 As shown in the figure, it can be seen that the XRD pattern of the sample has a very obvious diffraction peak on the crystal plane (001). Compared with the typical amorphous sample of boehmite, the peak is sharper and stronger. The layered hydrogen bond network of aluminum hydroxide is stable, so it requires higher energy. The boehmite layers are only bonded by weak van der Waals forces, which makes it easier to dissociate into an amorphous structure. In addition, there are fewer surface hydroxyl groups, which makes it easier to convert into an amorphous state.

Claims

1. A method for preparing amorphous hydrated aluminum oxide, characterized in that: The following steps are involved: (1) Weigh a certain amount of different hydrated alumina powders, place them in an agate ball mill, place zirconium balls with a certain ball-to-material ratio, and mill them in a planetary ball mill at a certain speed for a period of time to obtain powder A; (2) Powder A was taken out, placed in an agate mortar, and ground at room temperature for 20 min to obtain powder B.

2. The method for preparing amorphous hydrated aluminum oxide according to claim 1, wherein: The precursor powders are boehmite, pseudo-boehmite and aluminum hydroxide.

3. The method for preparing amorphous hydrated alumina according to claim 1, wherein: The ball-to-material ratio is 5 / 1-15 / 1.

4. The method for preparing amorphous hydrated aluminum oxide according to claim 1, wherein: The ball milling time is 10-48h.

5. The method for preparing amorphous hydrated aluminum oxide according to claim 1, wherein: The ball mill has a rotation speed of 400-700 r / min.

Images