Preparation method of alkali metal hydrogen storage material

Abstract

The invention discloses a preparation method of an alkali metal hydrogen storage material, and the preparation method comprises the following steps: in an inactive atmosphere, enabling a mixture containing alkali metal, an organic solvent and a diluent to be in contact with hydrogen, and carrying out ball milling to obtain the alkali metal hydrogen storage material. According to the invention, the alkali metal reacts with hydrogen under the assistance of the organic solvent and the diluent under the mechanical acting force to obtain the corresponding alkali metal hydride, and meanwhile, the diluent can be used as a catalyst of a subsequent hydrogen storage material or play a role in inhibiting sample agglomeration; and the residual organic solvent or diluent can be removed through at least one of the steps of calcining, purging, vacuumizing and the like according to requirements, so that a product with higher purity is obtained. The preparation method of the alkali metal hydride hydrogen storage material is high in synthesis efficiency, and the mechanically activated alkali metal hydride can be used as a reducing agent to be combined with other substances, is used for hydrogen storage and hydrogen production systems, and has good application prospect and value in the field of hydrogen storage.

Description

Technical Field

[0001] The present application relates to a method for preparing an alkali metal hydrogen storage material, and belongs to the technical field of material preparation and hydrogen storage application. Background Art

[0002] Hydrogen has been considered an ideal clean energy carrier due to its high combustion efficiency, abundant resources, diverse uses, and environmental friendliness. Alkali metal hydrides are considered to be one of the most promising hydrogen raw materials because of their high hydrogen storage capacity, but their decomposition temperature is too high to be used alone as hydrogen generation materials. Mechanically activated alkali metal hydrides can be combined with other substances for hydrogen storage and production systems, such as MH-LiNH2, 2MH-Mg(NH2)2, MH-NH3, MH-LiBH4, MH-H2O, and MH-CH4. Among them, the reactive composite hydride system represented by 2LiH-Mg(NH2)2 has a hydrogen storage capacity of 5.6wt%, and its theoretical enthalpy is low (△H=40kJ / mol-H2), and it can release hydrogen at 90℃ under 1bar H2. In addition, mechanically activated alkali metal hydrides can react with CO2 at room temperature to release a large amount of hydrogen.

[0003] Traditional methods for preparing alkali metal hydrides include direct reaction of metals with hydrogen, oxidation-reduction method, organic compound decomposition method and double decomposition method. However, the direct hydrogenation method requires high temperature and high pressure (the production of high-purity lithium hydride usually requires a reaction temperature of >700°C), production safety is worrying, and the operation is difficult. The oxidation-reduction method has harsh reaction conditions and can only be achieved at high temperatures, so it has little practical value. The organic compound decomposition method and double decomposition method face problems such as low atomic utilization and high cost, making them difficult to mass produce. Significantly refining light metal particles to the nanoscale can shorten the diffusion path of hydrogen, but most light metals are soft in texture, have a low Mohs hardness, and have a certain viscosity and are easy to agglomerate, making them difficult to refine; therefore, it is urgent to develop an easy-to-operate, safe and reliable preparation process for the production of alkali metal hydrides. Summary of the invention

[0004] In order to make up for the shortcomings of the above-mentioned existing preparation technology, the present invention proposes a method for preparing alkali metal hydride hydrogen storage materials. The method has mild reaction conditions and high synthesis efficiency. The prepared material can directly react with CO2 to release hydrogen or be combined with other substances for hydrogen storage. It has good development prospects and practical application value.

[0005] According to one aspect of the present application, a method for preparing an alkali metal hydrogen storage material is provided, the preparation method comprising:

[0006] Under an inert atmosphere, a mixture containing an alkali metal, an organic solvent, and a diluent is contacted with hydrogen and ball-milled to obtain the alkali metal hydrogen storage material;

[0007] The diluent is a solid non-reactive diluent.

[0008] Optionally, the solid non-reactive diluent is selected from oxides, carbon materials, x At least one of the compounds of the structure shown in R;

[0009] Wherein, 1≤x≤5, M is selected from at least one of Li, Na, K, Rb, and Cs,

[0010] R is selected from H - 、CO3 2- , Cl - Br - ,I - At least one of .

[0011] Optionally, the oxide is selected from at least one of titanium dioxide, zirconium oxide, niobium pentoxide and vanadium oxide.

[0012] Optionally, the carbon material is selected from at least one of graphite, acetylene black and carbon nanotubes.

[0013] Optionally, the organic solvent is selected from at least one of hydrocarbons, alcohols, ethers, amines, ketones, nitriles, pyridines and phenols.

[0014] Optionally, the hydrocarbon is selected from at least one of cyclohexane, pentane, hexane, n-heptane, isoprene, benzene and toluene.

[0015] Optionally, the alcohol is selected from at least one of methanol, ethanol, isobutanol and butanol.

[0016] Optionally, the ether is selected from at least one of ethylene oxide, tetrahydrofuran, dimethyl ether and ethyl ether.

[0017] Optionally, the amine is selected from at least one of trimethylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine.

[0018] Optionally, the ketone is selected from at least one of methyl butyl ketone, acetone, methyl isobutyl ketone and methyl ethyl ketone.

[0019] Optionally, the nitrile is selected from at least one of acetonitrile, acrylonitrile, propionitrile and adiponitrile.

[0020] Optionally, the pyridine is selected from at least one of pyridine, 2-methylpyridine, 3-methylpyridine and ethylpyridine.

[0021] Optionally, the phenols are selected from at least one of phenol, catechol and hydroquinone.

[0022] Optionally, the mass ratio of the alkali metal, the organic solvent and the diluent is: 1:0.05:0.05 to 1:5:5.

[0023] Optionally, the mass ratio of the alkali metal, the organic solvent and the diluent is independently selected from any value of 1:0.05:0.05, 1:0.1:0.1, 1:0.5:0.5, 1:2:2, 1:3:3, 1:5:5 or a range between any two of the above.

[0024] Optionally, the inert atmosphere is selected from at least one of helium, neon, argon, krypton and xenon.

[0025] Optionally, the pressure of the hydrogen is 5 to 100 bar.

[0026] Optionally, the pressure of the hydrogen is independently selected from any value among 5 bar, 10 bar, 15 bar, 20 bar, 25 bar, 50 bar, 75 bar, 80 bar, 100 bar or a range between any two of the above values.

[0027] Optionally, the ball milling further includes removing the organic solvent and the diluent.

[0028] Optionally, the removal method is selected from at least one of calcination, purging, and vacuuming.

[0029] Optionally, the ball milling method is selected from at least one of planetary ball milling, horizontal ball milling, and vibration ball milling.

[0030] Optionally, during the planetary ball milling, the ball milling temperature is -20 to 100°C.

[0031] Optionally, during the planetary ball milling, the ball milling temperature is independently selected from any value of -20°C, -10°C, 0°C, 10°C, 20°C, 50°C, 70°C, 100°C or a range between any two of the above.

[0032] Optionally, during the planetary ball milling, the rotation speed of the ball mill is 50 to 600 rpm, the ball milling time is 1 to 60 hours, and the ball-to-material ratio is 20:1 to 200:1.

[0033] Optionally, during the horizontal ball milling, the ball milling temperature is -20 to 100°C.

[0034] Optionally, during the horizontal ball milling, the ball milling temperature is independently selected from any value of -20°C, -10°C, 0°C, 10°C, 20°C, 50°C, 70°C, 100°C or a range between any two of the above values.

[0035] Optionally, during the horizontal ball milling, the rotation speed of the ball mill is 50 to 300 rpm, the ball-to-material ratio is 20:1 to 200:1, and the ball milling time is 1 to 60 hours.

[0036] Optionally, during the vibration ball milling, the ball milling temperature is -20 to 100°C.

[0037] Optionally, during the vibration ball milling, the ball milling temperature is independently selected from any value of -20°C, -10°C, 0°C, 10°C, 20°C, 50°C, 70°C, 100°C or a range between any two of the above.

[0038] Optionally, during the vibration ball milling, the vibration frequency of the ball milling is 1000 to 2000 times / min, the ball-to-material ratio is 20:1 to 200:1, and the ball milling time is 1 to 60 hours.

[0039] As a specific implementation, the present application is implemented through the following technical solutions:

[0040] A method for preparing an alkali metal hydride hydrogen storage material comprises the following steps:

[0041] (1) In a glove box with an argon atmosphere, the raw metal, a certain proportion of organic solvent and a solid non-reactive diluent are placed in a ball mill, and then hydrogen is introduced; the pressure of the hydrogen atmosphere is 5 to 100 bar;

[0042] (2) The organic solvent and the solid non-reactive diluent play a role in weakening the cold welding effect. The metal contacts with hydrogen and reacts under the action of mechanical grinding and ball milling. At the same time, the solid non-reactive diluent can be used as a catalyst for subsequent hydrogen storage materials or play an effect of inhibiting sample agglomeration. If necessary, the residual organic solvent or solid non-reactive diluent can be removed by at least one of the steps of calcination, purging, vacuuming, etc.

[0043] (3) exhausting the remaining gas after the reaction;

[0044] (4) Repeat steps (1) to (3) as needed.

[0045] Optionally, both the organic solvent and the solid non-reactive diluent are used as additives and neither is dispensable.

[0046] In the present application, alkali metals react with hydrogen under mechanical force with the assistance of organic solvents and solid non-reactive diluents to obtain corresponding alkali metal hydrides. At the same time, the solid non-reactive diluent can be used as a catalyst for subsequent hydrogen storage materials or to inhibit sample agglomeration. As needed, the residual organic solvent or solid non-reactive diluent can be removed by at least one of the steps of calcination, purging, and vacuuming to obtain a higher purity product. The preparation method of the alkali metal hydride hydrogen storage material has high synthesis efficiency, and the mechanically activated alkali metal hydride can be used as a reducing agent in combination with other substances for hydrogen storage and hydrogen production systems, which has good application prospects and value in the field of hydrogen storage.

[0047] The beneficial effects of this application include:

[0048] 1) The preparation method provided in the present application can efficiently convert alkali metals into alkali metal hydrides by simple ball milling under mild temperature and pressure conditions. It has high synthesis efficiency, can greatly reduce energy consumption, and is low-cost and suitable for large-scale production.

[0049] 2) The alkali metal hydride prepared by the preparation method provided in the present application can be directly used for hydrogen storage / release without further treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is the X-ray diffraction spectrum of the lithium hydride sample in Example 1 of the present application.

[0051] Figure 2 This is the appearance diagram of the sodium hydride sample in Example 3 of the present application.

[0052] Figure 3 This is the X-ray diffraction spectrum of the sodium hydride sample in Example 3 of the present application.

[0053] Figure 4 This is the appearance diagram of the comparison sample in comparative example 1 of this application.

[0054] Figure 5 This is the appearance diagram of the comparison sample in Comparative Example 2 of this application.

[0055] Figure 6 This is the appearance diagram of the comparison sample in Comparative Example 3 of this application. DETAILED DESCRIPTION

[0056] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0057] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0058] In this application, an X-ray diffractometer (XRD, X'Pert 3Alkali metal hydrides were characterized using a Materials Research Diffractometer, Malvern Panalytical).

[0059] Example 1

[0060] First, in an argon-protected glove box, 1.05 g of lithium particles and graphite were added to the stainless steel ball mill of the planetary ball mill at a mass ratio of 1:0.05, followed by 0.2 g of acetone, with a ball-to-material ratio of 90:1. 10 bar of hydrogen was introduced through the ball mill valve, and the ball mill speed was set to 200 rpm. The ball milling was performed for three minutes with a one-minute break. At room temperature, the ball milling was performed for 10 h to obtain the lithium hydride product.

[0061] Figure 1 This is the XRD pattern of the sample powder of Example 1. Its peak position matches that of the standard spectrum of lithium hydride, indicating that the sample synthesized by this preparation method is high-purity lithium hydride.

[0062] Example 2

[0063] First, in an argon-protected glove box, add 2 g of lithium particles and graphite in a mass ratio of 1:0.05 to the stainless steel ball mill of the planetary ball mill, then add 0.4 g of pyridine, and the ball-to-material ratio is 90:1. Then, introduce 30 bar of hydrogen through the ball mill valve, set the ball mill speed to 250 rpm, rest for one minute after every five minutes of ball milling, ball mill for 6 hours at room temperature, and evacuate under negative pressure for 10 hours to obtain a high-purity lithium hydride product.

[0064] Example 3

[0065] First, in an argon-protected glove box, 1.25 g of metallic sodium and sodium hydride were added to the stainless steel ball mill of the planetary ball mill at a mass ratio of 1:0.25, followed by 0.3 g of tetrahydrofuran, with a ball-to-material ratio of 140:1. 30 bar of hydrogen was introduced through the ball mill valve, and the ball mill speed was set to 200 rpm. The ball milling was performed for 5 minutes with a one-minute break, and hydrogen was added once every 5 hours of ball milling. The ball milling was repeated for 20 hours at room temperature to obtain the sodium hydride product.

[0066] Figure 2 This is the appearance of the sample of Example 3. The color of the sample is white-gray, which is similar to the color of commercial sodium hydride, indicating that the metallic sodium is completely hydrogenated and the obtained sodium hydride sample has high purity.

[0067] Figure 3 The XRD result of the sample in Example 3 shows a characteristic peak of sodium hydride, indicating that the method has successfully prepared sodium hydride.

[0068] Example 4

[0069] First, in an argon-protected glove box, 1.05 g of metallic sodium and sodium carbonate were added to the stainless steel ball mill of the planetary ball mill at a mass ratio of 1:0.05, and then 0.2 g of tetrahydrofuran was added, and the ball-to-material ratio was 110:1. 30 bar of hydrogen was introduced through the valve of the ball mill, and the ball mill speed was set to 200 rpm. The ball milling was performed for 5 minutes with a one-minute break, and hydrogen was replenished once every 5 hours of ball milling. The ball milling was repeated for 15 hours at room temperature, and the sample was calcined at 300°C for 3 hours under a hydrogen pressure of 5 bar to obtain a sodium hydride product with high crystallinity.

[0070] Example 5

[0071] First, in an argon-protected glove box, 1.05 g of metallic potassium and acetylene black were added to the stainless steel ball mill of the planetary ball mill at a mass ratio of 1:0.05, followed by adding 0.2 g of pyridine, with a ball-to-material ratio of 110:1, and then 10 bar of hydrogen was introduced through the ball mill valve, the ball mill speed was set to 200 rpm, and the ball milling was rested for one minute every 5 minutes. Hydrogen was replenished every 5 hours of ball milling, and reciprocating ball milling was performed at 100°C for 15 hours, and vacuum was evacuated under negative pressure for 12 hours to obtain a potassium hydride product with high crystallinity.

[0072] Example 6

[0073] First, in an argon-protected glove box, 1.05 g of metallic sodium and acetylene black were added to the stainless steel ball mill of the planetary ball mill at a mass ratio of 1:0.05, followed by adding 0.3 g of n-heptane, with a ball-to-material ratio of 180:1. 30 bar of hydrogen was introduced through the valve of the ball mill, and the ball mill speed was set to 200 rpm. The ball milling was performed for five minutes with a one-minute break, and hydrogen was replenished every five hours of ball milling. The ball milling was repeated for 15 hours at room temperature, and the product was evacuated under negative pressure for 12 hours to obtain a sodium hydride product with high crystallinity.

[0074] Comparative Example 1

[0075] In an argon-protected glove box, 0.5 g of metallic sodium was weighed and loaded into the stainless steel ball mill of the planetary ball mill, with a ball-to-material ratio of 90:1. 30 bar of hydrogen was introduced through the gas valve on the top of the ball mill, and the ball milling conditions were set as follows: a speed of 200 rpm, a one-minute break after every five minutes of ball milling, and ball milling for 20 hours at room temperature. The metallic sodium agglomerated during the ball milling process.

[0076] Figure 4 This is the appearance picture of the sample of comparative example 1. The metallic sodium gathers on the surface of the steel ball and still has an obvious metallic luster, indicating that the metallic sodium is not hydrogenated.

[0077] Comparative Example 2

[0078] In an argon-protected glove box, 0.8 g of metallic sodium and tetrahydrofuran were weighed in a mass ratio of 1:0.3 and loaded into the stainless steel ball mill of the planetary ball mill. Then 30 bar of hydrogen was introduced through the air valve on the top of the ball mill. The ball milling conditions were set as follows: ball-to-material ratio of 140:1, room temperature, rotation speed of 200 rpm, one minute break after every five minutes of ball milling, and ball milling for 20 hours. It was found that when there was no solid non-reactive diluent, the alkali metal agglomerated during the ball milling process.

[0079] Figure 5 This is the appearance of the sample of comparative example 2. Part of the surface of the comparative sample is purple, which may be due to the complexation between the organic solvent and the metallic sodium. However, most of the comparative sample is still metallic sodium, indicating that the metallic sodium is not hydrogenated.

[0080] Comparative Example 3

[0081] In an argon-protected glove box, weigh 1 g of metallic sodium and sodium hydride in a mass ratio of 1:1 and load them into the stainless steel ball mill of the planetary ball mill. Then introduce 30 bar of hydrogen through the air valve on the top of the ball mill. Set the ball milling conditions as follows: ball-to-material ratio 140:1, room temperature, rotation speed 200 rpm, mill for five minutes with a one-minute break, and reciprocate ball milling for 20 hours. It was found that when sodium hydride was present but no organic solvent was present, the alkali metal agglomerated during the ball milling process.

[0082] Figure 6 This is the appearance of the sample of Comparative Example 3. Sodium hydride powder is attached to the surface of the sample, but the inner layer is still metallic sodium.

[0083] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing an alkali metal hydrogen storage material, characterized in that: The preparation method comprises: Under an inert atmosphere, a mixture containing an alkali metal, an organic solvent, and a diluent is contacted with hydrogen and ball-milled to obtain the alkali metal hydrogen storage material; The diluent is a solid non-reactive diluent.

2. The preparation method according to claim 1, characterized in that: The solid non-reactive diluent is selected from oxides, carbon materials, x At least one of the compounds of the structure shown in R; Wherein, 1≤x≤5, M is selected from at least one of Li, Na, K, Rb, and Cs, R is selected from H - 、CO3 2- , Cl - Br - ,I - At least one of; Preferably, the oxide is selected from at least one of titanium dioxide, zirconium oxide, niobium pentoxide and vanadium oxide; Preferably, the carbon material is selected from at least one of graphite, acetylene black and carbon nanotubes.

3. The preparation method according to claim 1, characterized in that: The organic solvent is selected from at least one of hydrocarbons, alcohols, ethers, amines, ketones, nitriles, pyridines, and phenols; Preferably, the hydrocarbon is selected from at least one of cyclohexane, pentane, hexane, n-heptane, isoprene, benzene and toluene; Preferably, the alcohol is selected from at least one of methanol, ethanol, isobutanol and butanol; Preferably, the ether is selected from at least one of ethylene oxide, tetrahydrofuran, dimethyl ether and diethyl ether; Preferably, the amine is selected from at least one of trimethylamine, aniline, ethylenediamine, diisopropylamine and triethanolamine; Preferably, the ketone is selected from at least one of methyl butyl ketone, acetone, methyl isobutyl ketone and methyl ethyl ketone; Preferably, the nitrile is selected from at least one of acetonitrile, acrylonitrile, propionitrile and adiponitrile; Preferably, the pyridine is selected from at least one of pyridine, 2-methylpyridine, 3-methylpyridine and ethylpyridine; Preferably, the phenols are selected from at least one of phenol, catechol and hydroquinone.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the alkali metal, the organic solvent and the diluent is 1:0.05:0.05 to 1:5:

5.

5. The preparation method according to claim 1, characterized in that: The inert atmosphere is selected from at least one of helium, neon, argon, krypton and xenon; Preferably, the pressure of the hydrogen is 5 to 100 bar.

6. The preparation method according to claim 1, characterized in that: The ball milling also includes removing the organic solvent and the diluent; Preferably, the removal method is selected from at least one of calcination, purging and vacuuming.

7. The preparation method according to claim 1, characterized in that: The ball milling method is selected from at least one of planetary ball milling, horizontal ball milling and vibration ball milling.

8. The preparation method according to claim 7, characterized in that: During the planetary ball milling, the ball milling temperature is -20 to 100°C; Preferably, during the planetary ball milling, the rotation speed of the ball mill is 50 to 600 rpm, the ball milling time is 1 to 60 hours, and the ball-to-material ratio is 20:1 to 200:

1.

9. The preparation method according to claim 7, characterized in that: During the horizontal ball milling, the temperature of the ball milling is -20 to 100°C; Preferably, during the horizontal ball milling, the rotation speed of the ball mill is 50 to 300 rpm, the ball-to-material ratio is 20:1 to 200:1, and the ball milling time is 1 to 60 hours.

10. The preparation method according to claim 7, characterized in that: During the vibration ball milling, the ball milling temperature is -20 to 100°C; Preferably, during the vibration ball milling, the vibration frequency of the ball milling is 1000 to 2000 times / min, the ball-to-material ratio is 20:1 to 200:1, and the ball milling time is 1 to 60 hours.

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