Method for macroscopically preparing ultra-dispersed ferronickel iron talcum powder catalyst by utilizing nanobubble-assisted colloid mill

Abstract

The invention discloses a method for macroscopically preparing an ultra-dispersed ferronickel iron talcum powder catalyst by using a nano-bubble assisted colloid mill, which comprises the following steps: stirring a mixed metal salt solution and a mixed alkali solution into which nano-bubbles are introduced in advance in a colloid mill, introducing the nano-bubbles for aging, centrifuging after aging, taking solid precipitate, cleaning the solid precipitate, and drying to obtain the ultra-dispersed ferronickel iron talcum powder catalyst. And drying to obtain the NiFe-LDHs material. According to the preparation method, the colloid mill is utilized, violent stirring is carried out in a short time to trigger explosion nucleation of crystals, the nano-bubbles with negative charges are injected into the reactant slurry through the nano-bubble generator, uniform dispersion of the slurry is rapidly achieved, meanwhile, electrostatic force aggregation of NiFe-LDHs in the aging process is avoided, and finally the ultra-dispersed NiFe-LDHs powder is obtained. And the prepared ultra-dispersed NiFe-LDHs have excellent electrocatalytic activity and have a wide application prospect in the fields of hydrogen production by water electrolysis and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic nanomaterial preparation, and particularly relates to a method for preparing ultra-dispersed nickel-iron hydrotalcite powder catalyst in large quantities by using nano-bubble-assisted colloid mill. Background Art

[0002] Against the backdrop of global efforts to address climate change and seek sustainable energy solutions, hydrogen energy, as a clean, efficient energy carrier with broad application prospects, is gaining increasing attention.

[0003] With the ever-increasing demand for energy and increasingly stringent requirements for environmental protection, traditional hydrogen production from fossil fuels faces the dual pressures of limited resources and environmental pollution, seriously threatening the earth's ecological balance and human sustainable development. Therefore, the use of renewable energy-driven water electrolysis to produce hydrogen has become an important research direction in the energy field. The core of water electrolysis hydrogen production technology is the kinetically slow oxygen evolution reaction, and the smooth progress of the oxygen evolution reaction is inseparable from the participation of highly active and stable catalysts. Therefore, the rational design of oxygen evolution electrocatalysts with excellent activity and stability is the key to improving the efficiency of hydrogen production systems and promoting the commercial development of clean energy conversion technologies.

[0004] In recent years, nickel-iron hydrotalcites (NiFe-LDHs) have attracted widespread attention as potential alternatives to precious metal catalysts due to their low cost and high reactivity. Furthermore, the composition and structure of NiFe-LDHs catalysts are highly tunable. Their catalytic performance can be further optimized by varying the Ni / Fe ratio, doping with other elements, and manipulating their morphology and crystal planes. However, the cumbersome preparation process and poor stability currently limit the large-scale application of NiFe-LDHs catalysts. Commonly used methods for preparing NiFe-LDHs catalysts include coprecipitation, hydrothermal, sol-gel, and electrodeposition. These methods require stringent operating conditions and long preparation times ranging from hours to days. Furthermore, the prepared NiFe-LDHs are mostly one-dimensional powders, which can easily lead to entrapment of active sites during the spray coating process, severely reducing reactivity. Therefore, the rapid preparation of NiFe-LDHs catalysts with hierarchical structures has become a research hotspot. Summary of the Invention

[0005] The present invention is proposed to overcome the shortcomings of the existing technology of non-precious metal powder catalyst preparation process, such as complex preparation process, high temperature, high pressure, long time, small scale and other factors involved in the preparation method. Its purpose is to provide a method for preparing ultra-dispersed nickel-iron hydrotalcite powder catalyst in large quantities using nanobubble-assisted colloid mill.

[0006] The present invention is achieved through the following technical solutions: A method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid milling comprises the following steps: (I) preparing a mixed metal salt solution and a mixed alkali solution respectively, and introducing nanobubbles into the mixed metal salt solution; (II) adding the mixed alkali solution and the mixed metal salt solution into which nanobubbles have been introduced into the colloid mill simultaneously and stirring; (III) introducing nanobubbles into the solution stirred in step (II) for aging; (IV) centrifuging the aged solution from step (III) to obtain a solid precipitate; (V) Washing the solid precipitate obtained in step (IV) until the washing liquid becomes neutral, and then vacuum drying to obtain an ultra-dispersed nickel-iron hydrotalcite powder catalyst.

[0007] In the above technical solution, the mixed metal salt solution is a mixed aqueous solution of nickel nitrate and ferric nitrate; the concentration of nickel nitrate in the mixed metal salt solution is 0.1 mol / L~0.5 mol / L; the concentration of ferric nitrate in the mixed metal salt solution is 0.1 mol / L~0.5 mol / L; the molar ratio of nickel nitrate to ferric nitrate in the mixed metal salt solution is (1~5):1.

[0008] In the above technical solution, the mixed alkaline solution is a mixed aqueous solution of sodium hydroxide and sodium carbonate; the concentration of sodium hydroxide in the mixed alkaline solution is 0.1 mol / L~1 mol / L; the concentration of sodium carbonate in the mixed alkaline solution is 0.1 mol / L~0.5 mol / L; the molar ratio of sodium hydroxide to sodium carbonate in the mixed alkaline solution is (1~2):1.

[0009] In the above technical solution, the gas of the nanobubbles in step (I) is any one of CO2, O2 or N2; the ventilation time of the nanobubbles in step (I) is 5 min to 30 min.

[0010] In the above technical solution, the rotation speed of the colloid mill during stirring in step (II) is 1000 rpm to 5000 rpm, preferably 3000 rpm to 5000 rpm; the stirring time of the colloid mill in step (II) is 1 min to 5 min, preferably 3 min to 5 min.

[0011] In the above technical solution, the aging conditions in step (III) are normal temperature and pressure, and the aging time is 1 h to 10 h.

[0012] In the above technical solution, the centrifugal speed in step (IV) is 4000 rpm / min to 8000 rpm / min, preferably 6000 rpm / min to 8000 rpm / min; the centrifugal time is 1 min to 4 min, preferably 2 min to 4 min.

[0013] In the above technical solution, the cleaning in step (V) is carried out with deionized water and ethanol; the number of cleanings is 3 to 5 times with deionized water and 1 to 2 times with ethanol; the vacuum drying conditions are: drying at 60°C for 24 hours.

[0014] A super-dispersed nickel-iron hydrotalcite powder catalyst is prepared by the above method.

[0015] The beneficial effects of the present invention are: The present invention provides a method for preparing ultra-dispersed nickel-iron hydrotalcite powder catalysts in large quantities using a nanobubble-assisted colloid mill. By simultaneously adding two nanobubble-rich solutions, a mixed metal salt solution and a mixed alkali solution, to the colloid mill, ultra-dispersed hydrotalcite nanosheets with uniform particle size are obtained under the action of a strong shear force field caused by vigorous circulatory stirring in the colloid mill, thereby achieving rapid batch preparation of the catalyst. Compared with other methods, the method is environmentally friendly and energy-saving, has universal applicability, is easy to separate, and the product can be prepared in large quantities, which is conducive to narrowing the gap between laboratory research and industrial application.

[0016] The present invention utilizes a colloid mill to vigorously stir in a short period of time to induce explosive nucleation of crystals, and injects negatively charged nanobubbles into the reactant slurry through a nanobubble generator, quickly achieving uniform dispersion of the slurry while avoiding electrostatic aggregation of NiFe-LDHs during the aging process, ultimately obtaining ultra-dispersed NiFe-LDHs powder. The method of the present invention can significantly reduce the complexity of the process for preparing non-precious metal powder catalysts, avoid the high temperature, high pressure, long time, small scale and other factors involved in traditional preparation methods, and can achieve rapid batch preparation of catalysts. The ultra-dispersed NiFe-LDHs prepared by the method of the present invention have excellent electrocatalytic activity and have broad application prospects in fields such as water electrolysis and hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a digital photo of the NiFe-LDHs catalyst prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the NiFe-LDHs catalyst prepared in Example 1 of the present invention; Figure 3 This is a transmission electron micrograph of the NiFe-LDHs catalyst prepared in Example 1 of the present invention; Figure 4Graph showing the catalytic performance of the NiFe-LDHs catalysts prepared in Examples 1 to 3 of the present invention.

[0018] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0020] Example 1 Dissolve 26.17 g (0.3 mol / L) nickel nitrate hexahydrate and 12.12 g (0.1 mol / L) ferric nitrate nonahydrate in 300 ml of deionized water to form a mixed metal salt ion solution, designated as solution A. Dissolve 7.68 g of sodium hydroxide and 6.36 g of anhydrous sodium carbonate in 300 mL of deionized water to form a mixed alkaline solution, which is recorded as solution B.

[0021] A nanobubble generator was used to introduce CO2 gas into liquid A for 30 minutes, and then liquid A and liquid B were poured into a colloid mill at the same time and stirred for 3 minutes at a speed of 3000 rpm to obtain a mixed slurry. Then, a nanobubble generator was used again to introduce CO2 gas into the mixed slurry at room temperature and pressure for 1 hour; the mixed slurry was centrifuged at 6000 rpm for 3 minutes, washed three times with water, washed twice with ethanol, and finally dried in a vacuum oven.

[0022] The digital photos and electron microscope images of the obtained NiFe-LDHs catalyst are as follows: Figures 1-3 As shown in the figure, it can be seen that the prepared NiFe-LDHs catalyst is a light yellow powder, and its microstructure is an ultra-dispersed nanosheet structure of uniform size, which has the 101 characteristic crystal plane of NiFe-LDHs.

[0023] Example 2 Dissolve 26.17 g (0.3 mol / L) nickel nitrate hexahydrate and 12.12 g (0.1 mol / L) ferric nitrate nonahydrate in 300 ml of deionized water to form a mixed metal salt ion solution, designated as solution A. Dissolve 7.68 g of sodium hydroxide and 6.36 g of anhydrous sodium carbonate in 300 mL of deionized water to form a mixed alkaline solution, which is referred to as solution B. Liquid A was bubbled with CO2 for 30 minutes using a nanobubble generator. Liquids A and B were then poured simultaneously into a colloid mill and stirred for 3 minutes at 3000 rpm to produce a mixed slurry. The nanobubble generator was then used again to bubble CO2 through the mixed slurry for 4 hours at room temperature and pressure. The mixed slurry was then centrifuged at 6000 rpm for 3 minutes, washed three times with water, twice with ethanol, and finally dried in a vacuum oven.

[0024] Example 3 Dissolve 26.17 g (0.3 mol / L) nickel nitrate hexahydrate and 12.12 g (0.1 mol / L) ferric nitrate nonahydrate in 300 ml of deionized water to form a mixed metal salt ion solution, designated as solution A. Dissolve 7.68 g of sodium hydroxide and 6.36 g of anhydrous sodium carbonate in 300 mL of deionized water to form a mixed alkaline solution, which is referred to as solution B. Liquid A was bubbled with CO2 gas for 30 min using a nanobubble generator. Liquids A and B were then poured into a colloid mill and stirred for 3 min at 3000 rpm to obtain a mixed slurry. The nanobubble generator was then used again to bubble CO2 gas into the mixed slurry at room temperature and pressure for 6 h. The mixed slurry was centrifuged at 6000 rpm for 3 min, washed three times with water, washed twice with ethanol, and finally dried in a vacuum oven.

[0025] The catalytic performance of the obtained NiFe-LDHs catalyst is shown in Figure 2. Figure 4 As shown in the figure, it can be seen that NiFe-LDHs aged for 4 h has the best OER activity.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other.

[0027] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill, characterized in that: The following steps are involved: (I) preparing a mixed metal salt solution and a mixed alkali solution respectively, and introducing nanobubbles into the mixed metal salt solution; (II) adding the mixed alkali solution and the mixed metal salt solution into which nanobubbles have been introduced into the colloid mill simultaneously and stirring; (III) introducing nanobubbles into the solution stirred in step (II) for aging; (IV) centrifuging the aged solution from step (III) to obtain a solid precipitate; (V) Washing the solid precipitate obtained in step (IV) until the washing liquid becomes neutral, and then vacuum drying to obtain an ultra-dispersed nickel-iron hydrotalcite powder catalyst.

2. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The mixed metal salt solution is a mixed aqueous solution of nickel nitrate and ferric nitrate; the concentration of nickel nitrate in the mixed metal salt solution is 0.1 mol / L~0.5 mol / L; the concentration of ferric nitrate in the mixed metal salt solution is 0.1 mol / L~0.5 mol / L; the molar ratio of nickel nitrate to ferric nitrate in the mixed metal salt solution is (1~5):

1.

3. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The mixed alkaline solution is a mixed aqueous solution of sodium hydroxide and sodium carbonate; the concentration of sodium hydroxide in the mixed alkaline solution is 0.1 mol / L~1 mol / L; the concentration of sodium carbonate in the mixed alkaline solution is 0.1 mol / L~0.5 mol / L; the molar ratio of sodium hydroxide to sodium carbonate in the mixed alkaline solution is (1~2):

1.

4. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The gas of the nanobubbles in step (I) is any one of CO2, O2 or N2; the ventilation time of the nanobubbles in step (I) is 5 min to 30 min.

5. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The rotation speed of the colloid mill during stirring in the step (II) is 1000 rpm to 5000 rpm; the stirring time of the colloid mill in the step (II) is 1 min to 5 min.

6. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The aging conditions in step (III) are normal temperature and pressure, and the aging time is 1 h to 10 h.

7. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: The centrifugal speed in step (IV) is 4000 rpm / min to 8000 rpm / min; the centrifugal time is 1 min to 4 min.

8. The method for preparing a large amount of ultra-dispersed nickel-iron hydrotalcite powder catalyst using nanobubble-assisted colloid mill according to claim 1, characterized in that: In step (V), the cleaning is performed with deionized water and ethanol; the cleaning times are 3 to 5 times with deionized water and 1 to 2 times with ethanol; and the vacuum drying conditions are: drying at 60° C. for 24 h.

9. An ultra-dispersed nickel-iron hydrotalcite powder catalyst, characterized in that: Prepared by the method according to any one of claims 1 to 8.

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