Nano aluminum powder electrolysis preparation method based on ionic liquid

Abstract

The invention belongs to the technical field of light metal smelting and nano materials, and particularly discloses a nano aluminum powder electrolysis preparation method based on ionic liquid. The method comprises the following steps: mixing an ionic liquid, an additive and AlCl3 to obtain an electrolyte, and carrying out an electrolytic reaction by taking aluminum as a cathode and an inert electrode as an anode to prepare nano aluminum powder; the additive is specifically halide salt. The halide salt is added as an additive and can partially replace ionic liquid, so that the preparation cost of the nano aluminum powder is reduced; in addition, the halide salt can also avoid the phenomenon that the aluminum powder is adhered to the cathode, so that the particle size of the obtained nano aluminum powder becomes smaller and is more uniform, the nano aluminum powder with narrower particle size distribution is obtained, and the related performance during application is improved. The preparation method disclosed by the invention also has the advantages of low electrolysis temperature and low energy consumption, and the reaction can be protected by adopting a protective atmosphere in the electrolysis process, so that the preparation safety of the aluminum powder is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of light metal smelting and nanomaterials, and in particular to a method for preparing nano aluminum powder by electrolysis based on ionic liquid. Background Art

[0002] Aluminum is the second most valuable metal after steel. Currently, the Hall-Héroult process, also known as cryolite-alumina molten salt electrolysis, is widely used for industrial aluminum production. While this process is mature, it suffers from high energy consumption, severe pollution, and low product quality. In today's climate of promoting scientific development and energy conservation and emission reduction, there is an urgent need for technological innovation and energy-saving improvements in the aluminum electrolysis industry to promote product upgrades.

[0003] Among aluminum-related products, nano-aluminum has high economic added value and great application potential. Research has shown that when aluminum is reduced to the nanometer level, due to its ultra-high specific surface area effect and chemical activity, nano-aluminum powder becomes a high-energy metal fuel with excellent combustion properties, such as easy ignition, low combustion oxygen consumption, and high combustion heat. When nano-aluminum powder is used as an additive in solid fuel, its combustion rate is multiplied compared to submicron aluminum powder, significantly increasing the overall thrust performance of rockets and is widely used in aerospace, chemical, metallurgical, and military industries. In addition, nano-aluminum powder also has potential applications in hydrogen production, solar cells, and super thermite.

[0004] Traditional methods for preparing nano-aluminum powder mainly include physical methods, liquid phase methods, and gas phase methods. All of the above methods have various problems and are intermittent operations, making them unsuitable for large-scale industrial production.

[0005] Ionic liquids are salts composed entirely of cations and organic / inorganic anions. Their main characteristics include a wide liquid range, low vapor pressure, good conductivity, and a wide electrochemical window (up to 4-6V). They can be used as electrolytes for the electrodeposition of active metals. Studies have shown that ionic liquid electrolytes prepared with AlCl3 as an aluminum source can be successfully used for the electrodeposition of aluminum, thus forming ionic liquid aluminum electrolysis technology. Although this technology has advantages such as low operating temperature, short preparation process, and no pollutant emissions, it still has the problem of large aluminum powder particle size, wide particle size distribution range, and easy adhesion to the cathode, making it difficult to collect. This restricts the application of nano-aluminum powder in high-end fields and seriously affects the efficiency of large-scale industrial production. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing nano-aluminum powder by electrolysis based on ionic liquid, which solves the problem that the nano-aluminum powder prepared by the existing ionic liquid electrolysis method has a large particle size and a relatively dispersed particle size distribution, and at the same time avoids the problem that the prepared nano-aluminum powder is easy to adhere to the cathode and is difficult to collect.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing nano-aluminum powder by electrolysis based on ionic liquid comprises the following steps:

[0009] The ionic liquid, additives and AlCl3 are mixed to obtain an electrolyte, and an electrolytic reaction is carried out with aluminum as the cathode and an inert electrode as the anode to obtain nano-aluminum powder;

[0010] The additive is a halide salt.

[0011] Preferably, the molar ratio of the ionic liquid, the additive and AlCl3 is 1:0.01-0.1:1.5-2.

[0012] Preferably, the cation of the ionic liquid includes one or more of imidazolium cations, pyridinium cations, pyrrole cations and quaternary ammonium cations;

[0013] The anions of the ionic liquid are halogen anions.

[0014] Preferably, the temperature of the electrolysis reaction is 25-70°C, the time of the electrolysis reaction is 5-40 hours, and the current density of the electrolysis reaction is 3-40 mA / cm 2 .

[0015] Preferably, the inert electrode includes one or more of a glassy carbon electrode, a platinum electrode and a graphite electrode.

[0016] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The electrolytic preparation method of nano-aluminum powder disclosed in the present invention has the advantages of a short process, low electrolysis temperature and energy consumption. The generated aluminum powder has a controllable particle size, high purity and low oxygen content. In addition, a protective atmosphere can be used to protect the reaction during the electrolysis process, greatly improving the safety of aluminum powder preparation.

[0018] 2. The present invention can replace part of the ionic liquid to a certain extent by adding halide salt as an additive, thereby reducing the preparation cost; more importantly, the addition of halide salt can increase the cathode polarization, thereby refining the grains, making the obtained nano aluminum powder particle size smaller and more uniform, and can obtain nano aluminum powder with a narrower particle size distribution, thereby improving the relevant performance during application; it can also avoid the phenomenon of aluminum powder adhering to the cathode, which is of great significance for the large-scale industrial production of nano aluminum powder. DETAILED DESCRIPTION

[0019] The present invention provides a method for preparing nano-aluminum powder by electrolysis based on ionic liquid, comprising the following steps:

[0020] The ionic liquid, additives and AlCl3 are mixed to obtain an electrolyte, and an electrolytic reaction is carried out with aluminum as the cathode and an inert electrode as the anode to obtain nano-aluminum powder.

[0021] In the present invention, the additive is a halide salt, specifically one or more of chloride, bromide, and iodide; preferably, sodium chloride. The addition of the inorganic additive in the present invention can increase cathode polarization, thereby increasing the overpotential on the cathode surface, accelerating the reduction rate of metal ions on the cathode surface, increasing the nucleation driving force, and thereby increasing the rate of nucleation formation, thereby reducing the grain size and obtaining nano-aluminum powder with uniform and small particle size. The additives added in the present invention function differently from the additives added in prior studies using ionic liquid electroplating. The additives are added during electroplating to make the deposited aluminum layer dense and smooth, acting as brighteners and levelers.

[0022] In the present invention, the molar ratio of the ionic liquid, the additive and AlCl3 is 1:0.01-0.1:1.5-2, preferably 1:0.02-0.08:1.6-1.9, and more preferably 1:0.05:1.8.

[0023] In the present invention, the cations of the ionic liquid include one or more of imidazolium cations, pyridinium cations, pyrrole cations and quaternary ammonium cations.

[0024] In the present invention, the structural formula of the imidazolium cation is: The structural formula of the pyridinium cation is: The structural formula of the pyrrole cation is: The structural formula of the quaternary ammonium cation is:

[0025] In the present invention, R1, R2, R3, R4, R5, and R6 in the above-mentioned cations are independently one or more of methyl, ethyl, propyl, butyl, phenyl, and isomers thereof.

[0026] In the present invention, the anion of the ionic liquid is a halogen anion, specifically one or more of chloride ion, bromide ion and iodide ion.

[0027] In the present invention, the halogen ions in the additive halogenated salt are preferably the same as the halogen ions in the ionic liquid.

[0028] In the present invention, the temperature of the electrolysis reaction is 25-70°C, specifically 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, and 65°C; the time of the electrolysis reaction is 5-40h, specifically 10h, 15h, 20h, 25h, 30h, and 35h; the current density of the electrolysis reaction is 3-40mA / cm 2 , specifically 5mA / cm 2 , 8mA / cm 2 , 10mA / cm 2 , 12mA / cm 2 , 15mA / cm 2 , 18mA / cm 2 , 20mA / cm 2 , 22mA / cm 2 , 25mA / cm 2 , 28mA / cm 2 、30mA / cm 2 、32mA / cm 2 、35mA / cm 2 、38mA / cm 2 .

[0029] In the present invention, the inert electrode includes one or more of a glassy carbon electrode, a platinum electrode and a graphite electrode.

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] The ionic liquid 1-ethyl-3-methylimidazolium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.05:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was tested at 25°C and 3 mA / cm 2 Electrolysis was carried out for 36 hours under the above conditions to obtain nano-aluminum powder.

[0033] Example 2

[0034] The ionic liquid 1-ethyl-3-methylimidazolium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.1:1.5 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was tested at 25°C and 15 mA / cm 2 Electrolysis was performed under the following conditions for 12 h to obtain nano-aluminum powder.

[0035] Example 3

[0036] The ionic liquid 1-ethyl-3-methylimidazolium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.01:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was heated at 25 ° C and 25 mA / cm 2 Electrolysis was performed under the following conditions for 8 h to obtain nano-aluminum powder.

[0037] Example 4

[0038] The ionic liquid 1-ethyl-1-methylpyridinium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.01:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was tested at 25°C and 3 mA / cm 2 Electrolysis was performed under the following conditions for 40 h to obtain nano-aluminum powder.

[0039] Example 5

[0040] The electrolyte was obtained by mixing ionic liquid 1-ethyl-1-methylpyrrole chloride, sodium chloride and AlCl3 in a molar ratio of 1:0.01:2. Then, an aluminum plate was used as cathode, a glassy carbon electrode was used as anode, and a nitrogen atmosphere was used as a protective atmosphere. The electrolyte was obtained by mixing ionic liquid 1-ethyl-1-methylpyrrole chloride, sodium chloride and AlCl3 in a molar ratio of 1:0.01:2 ... 2 Electrolysis was performed for 24 hours under the above conditions to obtain nano-aluminum powder.

[0041] Example 6

[0042] The ionic liquid trimethylphenylammonium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.01:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was tested at 25 ° C and 3 mA / cm 2 Electrolysis was performed under the following conditions for 40 h to obtain nano-aluminum powder.

[0043] Example 7

[0044] The ionic liquid 1-ethyl-3-methylimidazolium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.05:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was heated at 70 ° C and 40 mA / cm 2Electrolysis was performed under the following conditions for 5 h to obtain nano-aluminum powder.

[0045] Example 8

[0046] The ionic liquid 1-ethyl-1-methylpyrrole bromide, sodium bromide and AlCl3 were mixed in a molar ratio of 1:0.01:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was tested at 70 ° C and 10 mA / cm 2 Electrolysis was performed for 24 hours under the above conditions to obtain nano-aluminum powder.

[0047] Example 9

[0048] The ionic liquid trimethylphenylammonium chloride, sodium chloride and AlCl3 were mixed in a molar ratio of 1:0.01:2 to obtain an electrolyte. Then, an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere. The electrolyte was heated at 70 ° C and 35 mA / cm 2 Electrolysis was performed under the following conditions for 12 h to obtain nano-aluminum powder.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is only that no sodium chloride is added.

[0051] Specifically, the ionic liquid 1-ethyl-3-methylimidazolium chloride and AlCl3 were mixed in a molar ratio of 1:2 to obtain an electrolyte, and then an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere at 25°C and 3 mA / cm 2 Electrolysis was carried out for 36 hours under the above conditions to obtain nano-aluminum powder.

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 3 is only that no sodium chloride is added.

[0054] Specifically, the ionic liquid 1-ethyl-3-methylimidazolium chloride and AlCl3 were mixed in a molar ratio of 1:2 to obtain an electrolyte, and then an aluminum plate was used as the cathode, a glassy carbon electrode was used as the anode, and a nitrogen atmosphere was used as the protective atmosphere at 25°C and 25 mA / cm 2 Electrolysis was performed under the following conditions for 8 h to obtain nano-aluminum powder.

[0055] The average particle size, D50, and D90 of the nano-aluminum powder obtained in the embodiment of the present invention and comparative examples 1-2 were tested, and the test results are shown in Table 1.

[0056] Table 1 Particle size test results of nano aluminum powder obtained in Examples 1 to 9

[0057]

[0058] Table 1 shows that the nano-aluminum powder prepared in the present invention has a smaller and more concentrated particle size. Comparing Examples 1-3 with Comparative Examples 1-3, it can be seen that the present invention significantly reduces the particle size of the nano-aluminum powder by adding additives, resulting in a more concentrated particle size of the prepared nano-aluminum powder, successfully producing nano-aluminum powder with a narrow particle size distribution. Furthermore, the present invention also avoids the phenomenon of nano-aluminum powder sticking.

[0059] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0060] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing nano-aluminum powder by electrolysis based on ionic liquid, characterized in that: The steps include: The ionic liquid, additives and AlCl3 are mixed to obtain an electrolyte, and an electrolytic reaction is carried out with aluminum as the cathode and an inert electrode as the anode to obtain nano-aluminum powder; The additive is a halide salt.

2. The method for preparing nano-aluminum powder by electrolysis based on ionic liquid according to claim 1, characterized in that: The molar ratio of the ionic liquid, the additive and AlCl3 is 1:0.01-0.1:1.5-2.

3. The method for preparing nano-aluminum powder by electrolysis based on ionic liquid according to claim 2, characterized in that: The cation of the ionic liquid includes one or more of imidazolium cations, pyridinium cations, pyrrole cations and quaternary ammonium cations; The anions of the ionic liquid are halogen anions.

4. The method for preparing nano-aluminum powder by electrolysis based on ionic liquid according to any one of claims 1 to 3, characterized in that: The temperature of the electrolysis reaction is 25-70°C, the time of the electrolysis reaction is 5-40 hours, and the current density of the electrolysis reaction is 3-40 mA / cm 2 .

5. The method for preparing nano-aluminum powder by electrolysis based on ionic liquid according to claim 4, characterized in that: The inert electrode includes one or more of a glassy carbon electrode, a platinum electrode and a graphite electrode.

Images