Preparation method and preparation system of aluminane

Abstract

The invention discloses a preparation method and a preparation system of aluminane, and particularly relates to the technical field of hydrogen storage materials. According to the method, an aqueous solution is used as a hydrogen source, the aluminum alkane is prepared through a double-chamber electrolysis method, the system comprises a cathode electrolysis device, an anode electrolysis device and a metal catalytic membrane, and the metal catalytic membrane is arranged between the cathode electrolysis device and the anode electrolysis device. According to the method disclosed by the invention, the high-efficiency catalytic characteristic of the palladium-based metal catalytic membrane and the passing ability of hydrogen atoms are utilized, so that the high-safety normal-pressure preparation of the aluminane without gas participation in the whole process is realized, and the electrolyzed water and the preparation and synthesis of the aluminane are creatively and efficiently integrated; the invention provides a double-chamber integrated electrolytic synthesis system which takes an aqueous solution as a hydrogen source and is stable in current density, high in electrolytic efficiency, large in automation potential and safe. The preparation method and application of the preparation system enable industrialization and popularization of a solid hydrogen-based fuel system to be possible.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage materials, and particularly relates to a preparation method and a preparation system for alane. Background Art

[0002] Hydrogen has the characteristics of storing a large amount of chemical energy (142 MJ / kg), high efficiency, cleanness, and rich reserves, making it an ideal choice to replace fossil fuels.

[0003] However, how to store hydrogen is the key restricting the current research, development, and application of hydrogen energy. According to the storage state of hydrogen, hydrogen storage methods can be divided into gaseous hydrogen storage, liquid hydrogen storage, solid hydrogen storage, etc. Gaseous hydrogen storage generally stores hydrogen in a hydrogen tank in the form of high-pressure gas. This method has a low hydrogen storage capacity and poor safety, and its application is limited. Liquid hydrogen storage generally liquefies hydrogen and then stores it in a heat-insulating device. This method requires a large amount of energy to liquefy hydrogen, and in terms of economic benefits, it is not suitable for large-scale applications. Solid hydrogen storage generally stores hydrogen in the form of adsorbed state or hydride in hydrogen storage materials. Among them, metal hydride hydrogen storage has developed rapidly due to its high hydrogen storage capacity, safety, and reliability, and is currently the most mature and widely used hydrogen storage material. However, due to the low hydrogen storage capacity of traditional metal hydrides (such as rare earth-based AB5 type, titanium-zirconium Laves phase AB2 type, titanium-based AB type, V-based solid solution, etc.), which far cannot meet the use conditions of on-vehicle hydrogen storage, researchers at home and abroad have mainly focused on high-hydrogen-content materials such as light-element hydrides (such as aluminum hydride, borohydride, amino compound, magnesium-based material, etc.).

[0004] Among them, alane (AlH3) is a light metal hydride, with a high hydrogen storage capacity (10.1 wt.%) and a low molecular weight (30.0 g·mol -1 ), and its hydrogen storage performance can be modified by controlling the synthesis process, and it can release hydrogen controllably at a temperature below 200 °C. At the same time, alane has the advantages of high stability and non-toxicity. Therefore, alane is considered a hydrogen storage material with relatively promising application prospects.

[0005] To realize the application of alane materials as energy carriers, its synthesis process is one of the key technologies. How to efficiently obtain a large amount of alane with controllable properties is the key to determining whether it can enter the industrial hydrogen storage field. Currently, the methods for preparing alane mainly include liquid-phase synthesis method, direct hydrogenation method, mechanical ball milling method, supercritical method, and electrochemical synthesis method, etc.

[0006] In 2009, Zidan et al. reported a method for preparing AlH3 by electrolyzing a THF solution of NaAlH4, designing an electrolytic cycle for the renewable production of AlH3, thus solving the problem of thermodynamically uncontrollable preparation of non-solvated AlH3 in the traditional method. In the report in 2012, Zidan improved the original electrolytic process, replacing the original NaAlH4 with LiAlH4 and adding LiCl to the electrolyte solution, and found that the addition of LiCl could accelerate the progress of the original electrolytic reaction, significantly improving the speed and efficiency of the anodic precipitation process.

[0007] However, currently, similar methods for preparing alane usually use hydrogen as the hydrogen source to participate in the reaction, and its safety and efficiency still hinder the industrial application of alane as a hydrogen-based fuel. At the same time, currently, the main source of a large amount of green hydrogen is the electrolysis of water by green electricity. How to combine the currently booming technology of electrolyzing water to produce green hydrogen, prepare high-energy-density alane hydrogen storage materials locally, and effectively improve the efficiency and application scope of the hydrogen-based energy system is one of the keys to the rapid industrialization of the solid-state hydrogen fuel mode. Summary of the Invention

[0008] For this reason, the present invention provides a method and a preparation system for preparing alane to solve the above problems.

[0009] The solution of the present invention is different from the existing wet chemical condition electrolysis production of alane solution. The present invention does not need to electrolyze water into hydrogen first throughout the process, but generates hydrogen atoms and hydride ions in situ in the electrolysis system, and uses them as the hydrogen source, which is directly consumed immediately in the electrolyte to synthesize alane. The present invention directly transfers the hydrogen in the aqueous solution to alane through the process flow, without the generation of hydrogen throughout the process, thus avoiding a series of engineering safety problems related to the storage and transportation of hydrogen, reducing the implementation difficulty of the project, and effectively improving the safety of production.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] On the one hand, the present invention provides a method for preparing alane. The method uses an aqueous solution as the hydrogen source and realizes the preparation of alane by a two-chamber electrolysis method, including:

[0012] Cathode chamber electrolysis: This electrolysis process is carried out in an aqueous electrolyte solution. By applying a voltage between the electrodes, hydrogen atoms are formed on the cathode metal catalytic membrane;

[0013] Migration of hydrogen atoms: The hydrogen atoms migrate to the other side of the cathode through interlattice diffusion to participate in the anode chamber electrolysis;

[0014] Anode chamber electrolysis: This electrolysis process is carried out in an organic electrolyte solution. The electrolyte initially contains alane or Seeds, by applying a voltage between the electrodes, hydrogen atoms are further reduced to hydride ions on the cathode metal catalytic membrane, the metal aluminum source is anodized to aluminum ions at the anode, and the hydride ions react with AlH3 to generate react with aluminum ions to form alane, thereby realizing the continuous combination of the metal aluminum source and hydrogen atoms to prepare alane.

[0015] On the other hand, the present invention provides a preparation system for alane, the system includes a cathode electrolysis device, an anode electrolysis device and a metal catalytic membrane, and the metal catalytic membrane is arranged between the cathode electrolysis device and the anode electrolysis device.

[0016] Furthermore, the cathode electrolysis device is provided with a first electrolytic cell, wherein the electrolyte in the first electrolytic cell is an aqueous electrolyte.

[0017] Furthermore, the aqueous electrolyte is acidic, alkaline or neutral to adjust the difficulty of catalytically generating hydrogen atoms. As an example, dilute sulfuric acid solution is preferred, with a concentration preferably of 0.1 - 0.3 mol / L; sodium hydroxide solution is preferred, with a concentration preferably of 0.5 - 1.5 mol / L.

[0018] Furthermore, a first metal electrode is arranged in the first electrolytic cell.

[0019] Furthermore, the first metal electrode is selected from a platinum mesh, a platinum - ruthenium alloy mesh or a ruthenium - titanium alloy mesh; it is used to promote the electrolysis of aqueous solution to produce oxygen.

[0020] Furthermore, the anode electrolysis device is provided with a second electrolytic cell, wherein the electrolyte in the second electrolytic cell is an organic electrolyte; it is used to oxidize the metal aluminum source to aluminum ions and react with the medium in the electrolyte to form alane. As an example, the solute is a metal compound of, more preferably LiAlH4 and NaAlH4; the solute concentration is 0.1 - 2 mol / L, preferably 0.1 mol / L - 0.3 mol / L, and optionally LiCl can be added to the electrolyte to promote the reaction, with a concentration preferably of 0.05 mol / L - 0.15 mol / L. Additionally, a surfactant can be optionally added to the electrolyte, preferably a long - chain surfactant, with a concentration preferably of 0.0003 mol / L - 0.006 mol / L.

[0021] Furthermore, a second metal electrode is arranged in the second electrolytic cell, and its material is metal aluminum.

[0022] Furthermore, the second metal electrode is selected from aluminum powder, aluminum sheets or metal aluminum particles.

[0023] Further, the metal catalytic membrane is a palladium-based metal catalytic membrane; wherein, the palladium-based metal catalytic membrane comprises an alloy containing palladium. As an example, the thickness of the palladium-based metal catalytic membrane is preferably 5-15 μm; the palladium-based metal catalytic membrane is preferably a palladium-gold or palladium-silver alloy to improve the efficiency of catalytic hydrogen atom generation.

[0024] The metal catalytic membrane is used to isolate the electrolytes in the first electrolytic cell and the second electrolytic cell, catalytically reduce monovalent hydrogen to hydrogen atoms on the aqueous solution side, and further reduce the hydrogen atoms to hydride ions on the organic solution side to participate in the electrochemical reaction of the second electrolytic cell.

[0025] The present invention has the following advantages:

[0026] The present invention utilizes the high-efficiency catalytic characteristics of the palladium-based metal catalytic membrane and the passability of hydrogen atoms to achieve the preparation of high-safety green ambient-pressure alane without hydrogen participation throughout the process, creatively and efficiently integrates electrolytic water and alane preparation synthesis, provides a dual-chamber integrated electrolytic synthesis system with an aqueous solution as the hydrogen source, stable current density, high electrolysis efficiency, great automation potential, and safety. The preparation method of the present invention is of great significance for the further development of the hydrogen-based energy system.

[0027] The electrochemical method of the present invention can not only prepare high-purity alane, but also has the advantages of simple process conditions, continuous production, low synthesis cost, and high safety.

[0028] The preparation method of the present invention avoids the use of high-pressure hydrogen during the preparation process, reduces the requirements for the experimental environment and fire protection needs, and can effectively improve the convenience and efficiency of preparing alane by electrolysis; the present invention combines two cutting-edge technologies of electrolytic water hydrogen production and electrochemical synthesis of alane, expands the application scope of electrocatalytic synthesis, and provides a new path for the development of the hydrogen-based energy system; the device of the present invention makes full use of the original process equipment and facilities for electrolytic preparation of alane, and can be put into use only with simple modification, having great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, other implementation drawings can be obtained by extension based on the provided drawings without creative efforts.

[0030] The structures, ratios, sizes, etc. illustrated in this specification are only used to match the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention.

[0031] Figure 1 A preparation system for alane provided in Embodiment 1 of the present invention.

[0032] In the figure: 1 - First metal electrode; 2 - First electrolytic cell; 3 - Palladium-based metal catalytic membrane; 4 - Second electrolytic cell; 5 - Second metal electrode.

[0033] Figure 2 XRD pattern of AlH3 provided in Embodiment 1 of the present invention.

[0034] Figure 3 TEM image of AlH3 provided in Embodiment 1 of the present invention.

[0035] Figure 4 Thermogravimetric TGA curve of AlH3 provided in Embodiment 1 of the present invention. Specific implementation mode

[0036] The following specific embodiments illustrate the implementation mode of the present invention. Those familiar with this technology can easily understand other advantages and effects of the present invention from the content shown in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope protected by the present invention.

[0037] Principle:

[0038] H + +e - →H→H — -e - ;

[0039]

[0040] Al - 3e - →Al 3+ ;

[0041]

[0042] Embodiment 1

[0043] This embodiment provides a method for preparing alane. The preparation system is asFigure 1 As shown in:

[0044] The system includes a cathode electrolysis device, an anode electrolysis device, and a metal catalytic membrane. The metal catalytic membrane is disposed between the cathode electrolysis device and the anode electrolysis device;

[0045] The cathode electrolysis device is provided with a first electrolytic cell 2. Among them, the electrolyte in the first electrolytic cell 2 is 0.5 mol / L -1 sulfuric acid;

[0046] A first metal electrode 1 is disposed in the first electrolytic cell 2; The first metal electrode 1 uses a platinum mesh;

[0047] The anode electrolysis device is provided with a second electrolytic cell 4. Among them, the electrolyte in the second electrolytic cell 4 is a THF solution, and the solute is 0.2 mol / L -1 LiAlH4 and 0.1 mol / L -1 LiCl;

[0048] A second metal electrode 5 is disposed in the second electrolytic cell 4; The second metal electrode 5 uses an aluminum plate;

[0049] The metal catalytic membrane is a palladium-based metal catalytic membrane 3 and uses pure palladium; The thickness is 15 μm.

[0050] Preparation method: Apply voltages to the platinum mesh and the palladium-based metal catalytic membrane, and the aluminum plate and the palladium-based metal catalytic membrane respectively. Among them, the platinum mesh and the aluminum plate are at positive voltages, and the palladium-based metal catalytic membrane is at a negative voltage to form a conductive circuit and start electrolytic synthesis of alane.

[0051] Specifically: The palladium-based metal catalytic membrane catalyzes the formation of hydrogen atoms from monovalent hydrogen on the cathode palladium-based catalytic membrane on the aqueous solution side. The hydrogen atoms diffuse through the lattice to the organic solution side and are further reduced to hydride ions under the action of the palladium-based metal catalytic membrane. The hydride ions then react with AlH3 to generate The anode of the second electrolytic cell oxidizes the metal aluminum source into aluminum ions and reacts with the in the electrolyte to generate alane, so that alane is continuously generated during the entire electrolysis process. The XRD pattern of the obtained AlH3 sample is as Figure 2 shown, the TEM image is as Figure 3 shown, the TGA curve is as Figure 4 shown, the sample purity is 96%, and the particle size is 0.2 - 5 μm.

[0052] Example 2

[0053] This example provides a method for preparing alane:

[0054] Replace the electrolyte in the first electrolytic cell 2 with 1 mol / L sodium hydroxide solution, and adjust the pH value of the aqueous solution to optimize the hydrogen atom generation efficiency. The others are exactly the same as in Example 1.

[0055] The obtained AlH3 sample has a purity of 98% and a particle size of 0.2 - 6 μm.

[0056] Example 3

[0057] This example provides a method for preparing alane:

[0058] The metal catalytic membrane is a palladium-based metal catalytic membrane 3 using 95% Pd - 5% Au; with a thickness of 15 μm; to improve the efficiency of catalytic hydrogen atom generation and the hydrogen atom diffusion rate; the others are exactly the same as in Example 1.

[0059] The obtained AlH3 sample has a purity of 99% and a particle size of 0.5 - 4 μm.

[0060] Example 4

[0061] This example provides a method for preparing alane:

[0062] The metal catalytic membrane is a palladium-based metal catalytic membrane 3 using pure palladium; with a thickness of 5 μm; to optimize the hydrogen atom diffusion rate within the catalytic membrane lattice; the others are exactly the same as in Example 1.

[0063] The obtained AlH3 sample has a purity of 97% and a particle size of 0.3 - 5 μm.

[0064] Example 5

[0065] This example provides a method for preparing alane:

[0066] A second metal electrode 5 is provided in the second electrolytic cell 4; the second metal electrode 5 uses aluminum powder; to adjust the current density distribution and stabilize the electrolysis conditions; the others are exactly the same as in Example 1.

[0067] The obtained AlH3 sample has a purity of 98% and a particle size of 0.2 - 4 μm.

[0068] Example 6

[0069] This example provides a method for preparing alane:

[0070] The solute is selected as NaAlH4 to replace LiAlH4, and the others are exactly the same as in Example 1.

[0071] The obtained AlH3 sample has a purity of 97% and a particle size of 0.5 - 6 μm.

[0072] Comparative Example 1

[0073] In this comparative example, the palladium-based metal catalytic membrane is replaced with pure gold foil, and the others are exactly the same as in Example 1.

[0074] In this comparative example, AlH3 was generated with a purity of 96% and a particle size of 0.2 - 5 μm. However, due to the significantly lower catalytic effect of the pure gold foil compared to the palladium-based metal catalytic membrane and the difficulty of hydrogen atoms to effectively diffuse through the gold foil, at this time, the cathode electrolysis device and the anode electrolysis device are equivalent to a separated electrolytic water hydrogen production device and an electrolytic aluminum alkane preparation device. Hydrogen in water will escape as hydrogen gas at one end of the gold foil in the cathode electrolysis device and cannot be used as the hydrogen source for synthesizing aluminum alkane; on the side of the anode electrolysis device, the hydrogen in the electrolyte is the hydrogen source for synthesizing aluminum alkane, and the synthesis of aluminum alkane will cause continuous consumption of the electrolyte, making it impossible to achieve long-term continuous production of aluminum alkane.

[0075] Comparative Example 2

[0076] Set the metal electrode in the second electrolytic cell to a platinum mesh, and the rest is exactly the same as in Example 1.

[0077] In this comparative example, no new AlH3 was observed, and at the same time, bubbles were observed on the platinum mesh. After detection, the gas was hydrogen.

[0078] The present invention provides a method for electrolytically preparing aluminum alkane using an aqueous solution as the hydrogen source and a dual-chamber integrated electrolytic cell system, realizing a green atmospheric-pressure AlH3 preparation method without hydrogen participation throughout the process. It creatively combines electrolytic water and electrolytic synthesis of AlH3, laying a technical foundation for the large-scale practical application of high-energy-density aluminum alkane hydrogen storage materials.

[0079] Although the present invention has been described in detail with general descriptions and specific examples above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for preparing alane, characterized in that, The method uses an aqueous solution as a hydrogen source and realizes the preparation of alane through a two-chamber electrolysis method, including: Cathode chamber electrolysis: This electrolysis process is carried out in an aqueous electrolyte solution. By applying a voltage between the electrodes, hydrogen atoms are formed on the cathode metal catalytic membrane. Migration of hydrogen atoms: The hydrogen atoms migrate to the other side of the cathode through interlattice diffusion and participate in the anode chamber electrolysis. Anodic chamber electrolysis: This electrolysis process is carried out in an organic electrolyte solution, which initially contains alane or seeds. By applying a voltage between the electrodes, hydrogen atoms are further reduced to hydride anions on the cathode metal catalytic membrane, the metal aluminum source is oxidized to aluminum ions at the anode, and the hydride anions react with AlH3 to form which reacts with aluminum ions to form alane, thereby realizing the continuous combination of the metal aluminum source and hydrogen atoms to prepare alane.

2. A preparation system for alane, which prepares alane according to the preparation method described in claim 1, is characterized in that, The system includes a cathode electrolysis device, an anode electrolysis device, and a metal catalytic membrane. The metal catalytic membrane is arranged between the cathode electrolysis device and the anode electrolysis device.

3. The preparation system of an alane according to claim 2, characterized in that, The cathode electrolysis device is provided with a first electrolytic cell (2). Among them, the electrolyte in the first electrolytic cell (2) is an aqueous electrolyte solution.

4. The preparation system of an alane according to claim 3, wherein The aqueous electrolyte solution is acidic, alkaline, or neutral.

5. The preparation system of an alane according to claim 3, wherein, A first metal electrode (1) is arranged in the first electrolytic cell (2).

6. The preparation system of an alane according to claim 5, characterized in that, The first metal electrode (1) is selected from a platinum mesh, a platinum-ruthenium alloy mesh, or a ruthenium-titanium alloy mesh.

7. The preparation system of an alane according to claim 2, wherein, The anode electrolysis device is provided with a second electrolytic cell (4). Among them, the electrolyte in the second electrolytic cell (4) is an organic electrolyte solution.

8. The preparation system of an alane according to claim 7, characterized in that, A second metal electrode (5) is arranged in the second electrolytic cell (4).

9. The preparation system of an alane according to claim 8, characterized in that, The material of the second metal electrode (5) is metallic aluminum, including aluminum powder, aluminum sheets, or metallic aluminum particles.

10. The preparation system of an alane according to claim 2, wherein, The metal catalytic membrane is a palladium-based metal catalytic membrane (3); among them, the palladium-based metal catalytic membrane (3) includes an alloy containing palladium.

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