Alkali metal hydride, method of preparation and use
The ball milling method for preparing alkali metal hydrides at room temperature solves the problems of high energy consumption and hydrogen embrittlement caused by high-temperature preparation, and realizes efficient and low-cost preparation of alkali metal hydrides, which is suitable for hydrogen storage and catalytic synthesis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2022-11-17
- Publication Date
- 2026-06-09
AI Technical Summary
The preparation of common alkali metal hydrides requires high temperatures, which leads to high energy consumption and hydrogen embrittlement, limiting their industrial production and application.
Alkali metal hydrides are prepared at room temperature by ball milling raw materials containing alkali metals, organic solvents, and hydrogen under an inactive atmosphere. This includes selecting appropriate organic solvents and ball milling parameters, such as ball-to-material ratio, rotation speed, and hydrogen partial pressure, followed by calcination and purging to remove excess substances.
This method enables the efficient preparation of high-purity alkali metal hydrides at room temperature, simplifies the process, reduces energy consumption, and improves safety and economic efficiency, making it suitable for large-scale production.
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Figure CN118047352B_ABST
Abstract
Description
Technical Field
[0001] This application relates to an alkali metal hydride, its preparation method, and its application, belonging to the technical field of hydrogen storage materials and hydrogen storage applications. Background Technology
[0002] Metal hydrides, especially alkali metal hydrides, are widely used in inorganic and organic synthesis as reducing agents and sources of negative hydrogen ions. They also have broad application prospects in catalysis, such as in ammonia synthesis and decomposition. Furthermore, they can be used as hydrogen generators in field operations and wartime as a stable and reliable source of hydrogen, although convenient to use, they are expensive. In addition, research has shown that alkali metal hydrides have a strong hydrogen storage capacity due to the low molar mass of alkali metals. The density of hydrogen stored per unit volume and mass is much higher than that of gaseous hydrogen under the same temperature and pressure conditions. Since alkali metal hydrides are all solids, they do not require the large and bulky steel cylinders needed for storing high-pressure hydrogen, nor the extreme temperature conditions required for storing liquid hydrogen. Therefore, they also have broad application prospects in the field of hydrogen storage.
[0003] However, common alkali metal hydrides are ionic hydrides, usually formed when hydrogen gas directly combines with an alkali metal at a relatively high temperature, where the hydrogen atom gains an electron and becomes H. - The ions react to form ionic metal hydrides. This is because the reaction H₂ == H₂... - Δ r H>0 requires the absorption of heat, so ionic metal hydrides usually need to be generated at high temperatures. However, the hydrogen embrittlement problem caused by high temperatures and the high energy consumption greatly limit the industrial production of alkali metal hydrides. Summary of the Invention
[0004] This application provides a simple and easy method for preparing alkali metal hydrides. The method has mild reaction conditions, a simple preparation process suitable for large-scale production, and produces products with uniform particle size and high purity.
[0005] According to one aspect of this application, a method for preparing an alkali metal hydride is provided, the method comprising at least:
[0006] Under an inactive atmosphere, a raw material containing alkali metal, organic solvent, and hydrogen is ball-milled to obtain the alkali metal hydride.
[0007] Optionally, the organic solvent contains at least one of the functional groups of hydrocarbons, ketones, ethers, amines, alcohols, thiols, and esters.
[0008] Optionally, the organic solvent is selected from at least one of cyclohexane, isoprene, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, dimethyl ether, diethyl ether, trimethylamine, dimethylamine, methylamine, triethylamine, diethylamine, dimethylethanolamine, methyldiethanolamine, methanol, ethanol, butanol, methylcyclopentenolone, dimethylethanolamine, methyldiethanolamine, methanethiol, ethanethiol, ethylenedithiol, 1-propanethiol, ethyl formate, ethyl propionate, and methyl acetate.
[0009] Optionally, the mass ratio of the alkali metal to the organic solvent is 1:0.1 to 1:1.
[0010] Optionally, the mass ratio of the alkali metal to the organic solvent is selected from any value among 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, and 1:1, or a range between any two of the above.
[0011] Optionally, organic solvents participate in the reaction as reactants. During the reaction, the organic solvents chemically bond with the surface of the raw metal and change its surface activity, thereby reducing the cold welding effect and metal aggregation effect during the ball milling process.
[0012] Optionally, the alkali metal is selected from at least one of Li, Na, K, Rb, and Cs.
[0013] Optionally, the partial pressure of the hydrogen gas is 0.1 MPa to 10 MPa.
[0014] Optionally, the partial pressure of the hydrogen gas is selected from any value or range between any two points from 0.1MPa, 1MPa, 1.5MPa, 2.0MPa, 2.5MPa, 3.0MPa, 5.0MPa, 7.0MPa, 8.0MPa, and 10.0MPa.
[0015] Optionally, the mixing includes ball milling.
[0016] Optionally, the mechanical ball mill is a planetary ductile iron.
[0017] Optionally, the ball milling time is 1 to 60 hours, and the ball milling temperature is 0 to 100°C.
[0018] Optionally, the ball milling time is selected from any value or a range between any two points from 1h, 2h, 5h, 7h, 9h, 11h, 13h, 15h, 17h, 20h, 30h, 40h, and 60h.
[0019] Optionally, the temperature of the ball mill is selected from any value among 0℃, 10℃, 20℃, 40℃, 60℃, 80℃, and 100℃, or a range between any two of the above points.
[0020] Optionally, the ball milling time is 8 to 15 hours, and the ball milling temperature is 15 to 60°C.
[0021] Optionally, the mass ratio of the media balls to the raw material during the ball milling process is 20:1 to 120:1. Optionally, the mass ratio of the media balls to the raw material during the ball milling process is selected from any value or a range between any two points from 20:1, 40:1, 60:1, 80:1, 100:1, 110:1, and 120:1.
[0022] Optionally, the ball milling includes ball milling on a planetary ball mill, a horizontal ball mill, or a vibratory ball mill.
[0023] Optionally, the planetary ball mill rotates at a speed of 50 to 600 revolutions per minute.
[0024] Optionally, the rotational speed of the planetary ball mill is any value among 50 rpm, 100 rpm, 150 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, and 600 rpm, or a range between any two of the above points.
[0025] Optionally, the horizontal ball mill rotates at a speed of 50 to 300 revolutions per minute.
[0026] Optionally, the speed of the vibratory ball mill is 10 to 100 rpm, and the excitation frequency is 500 to 2000 times / min.
[0027] Optionally, the inactive atmosphere is selected from at least one of helium atmosphere, neon atmosphere, argon atmosphere, krypton atmosphere, and xenon atmosphere.
[0028] Optionally, the inactive atmosphere is an argon atmosphere.
[0029] Optionally, the ball milling process may further include at least one of calcination, purging, and vacuuming.
[0030] Optionally, the calcination atmosphere is hydrogen, the hydrogen back pressure is 0.1-3 MPa, the calcination temperature is 100-400℃, and the calcination time is 0.5-20 h.
[0031] Optionally, after ball milling, excess organic solvents or exhaust gases may be removed.
[0032] Optionally, the purging gas is selected from at least one of hydrogen, helium, neon, argon, krypton, and xenon.
[0033] Optionally, the vacuum level of the vacuum pump is less than 0.01 bar.
[0034] Alternatively, a vacuum method can be used to remove excess organic solvents that are physically adsorbed.
[0035] Optionally, the preparation method described above is suitable not only for preparing alkali metal hydrides, but also for preparing alkali metal powders. If the partial pressure of hydrogen gas introduced into the reactor is less than the equilibrium pressure or no hydrogen gas is introduced during the preparation process, the product is an alkali metal powder with a particle size significantly smaller than that of the raw material.
[0036] Ball milling offers advantages such as good operating conditions, reliable operation, inexpensive grinding media, and ease of large-scale production. Furthermore, the high energy content of ball milling is beneficial for the reaction, which takes place in a closed container, allowing for the introduction of inert gases instead of air and preventing the evaporation of organic solvents.
[0037] Optionally, this application provides a method for synthesizing alkali metal hydrides, comprising the following steps:
[0038] (1) Add the raw material metal and a certain proportion of organic solvent to the reactor under a protective atmosphere, and introduce hydrogen gas;
[0039] (2) Mechanical ball milling brings the metal into contact with hydrogen and causes it to react;
[0040] (3) Remove excess reaction exhaust gas;
[0041] (4) If necessary, steps 1-3 above may be repeated;
[0042] (5) If necessary, at least one step in the process of calcination, purging, vacuuming, etc., can be added to remove organic residues.
[0043] Optionally, in the implementation method, high-purity argon is selected as the inert atmosphere in step (1).
[0044] Optionally, a raw material metal and an organic solvent are added to the reactor and a certain amount of hydrogen is introduced to react and obtain an alkali metal hydride. The product with higher purity can be obtained by removing trace organic residues through at least one of the following steps: calcination, purging, and vacuuming.
[0045] Optionally, when the partial pressure of the hydrogen gas is less than the equilibrium pressure or no hydrogen gas is introduced, alkali metal powder is obtained.
[0046] According to another aspect of this application, an alkali metal hydride prepared by the preparation method described above is provided, characterized in that the general chemical formula of the alkali metal hydride is AH;
[0047] Wherein, A is selected from at least one of Li, Na, K, Rb, and Cs.
[0048] According to another aspect of this application, an alkali metal hydride prepared by the above-described preparation method is provided, and the application of at least one of the above-described alkali metal hydrides in a hydrogen storage material is provided.
[0049] The beneficial effects that this application can produce include:
[0050] 1) This invention provides a simple method for synthesizing alkali metal hydrides. It only requires a simple ball milling step to efficiently convert particulate alkali metals into alkali metal hydrides at room temperature, which greatly improves the safety and economic benefits of production.
[0051] 2) The preparation method provided by the present invention can efficiently hydrogenate alkali metals at room temperature without adding a catalyst, and the obtained alkali metal hydrides have high purity and excess reactants are easy to remove.
[0052] 3) The preparation method provided by the present invention is simple and can utilize existing industrial-grade ball mill jars and processes to make it possible to obtain kilogram-level or even ton-level alkali metal hydrides in a short time.
[0053] 4) The alkali metal hydrides described in this invention have uniform particle size and broad application prospects in hydrogen storage, heat storage, and catalytic synthesis. The preparation process is simple, suitable for large-scale, low-cost scaling, and has excellent development prospects and practical application value. Attached Figure Description
[0054] Figure 1 This is a comparison of the appearance of the lithium hydride product and the raw lithium particles in Example 1 of this application.
[0055] Figure 2 This is the XRD pattern of the lithium hydride product in Example 1 of this application.
[0056] Figure 3 This is an appearance diagram of the lithium hydride sample in Example 2 of this application.
[0057] Figure 4 This is the XRD pattern of the lithium hydride sample in Example 2 of this application.
[0058] Figure 5 This is an appearance diagram of sodium hydride in Example 3 of this application.
[0059] Figure 6 This is an appearance diagram of the comparative sample in Comparative Example 1 of this application.
[0060] Figure 7 This is the XRD pattern of the comparative sample in Comparative Example 1 of this application.
[0061] Figure 8 This is an appearance drawing of the product in Embodiment 9 of this application.
[0062] Figure 9 This is an appearance diagram of the comparative sample in Comparative Example 2 of this application. Detailed Implementation
[0063] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0064] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0065] The room temperature described in this application is 25°C.
[0066] The analysis method in the embodiments of this application is as follows:
[0067] XRD analysis was performed using an X'Pert3 X-ray powder crystal diffractometer.
[0068] Example 1
[0069] In an argon-protected glove box, 1g of lithium granules and cyclohexanone were weighed at a mass ratio of 1:0.2 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 1MPa was introduced through the gas valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio of 60:1, room temperature, rotation speed of 200 rpm, a one-minute break after every five minutes of ball milling, and hydrogen replenishment every five hours of ball milling. The process was repeated for 15 hours. The sample was then calcined at 300℃ for 3 hours under a hydrogen pressure of 1 bar to obtain a highly crystalline lithium hydride product.
[0070] Characterization:
[0071] The appearance of lithium hydride products compared to that of raw lithium: Figure 1 As can be seen, the lithium hydride product is a white powder with no metallic luster, indicating that the lithium metal is completely hydrogenated.
[0072] XRD results of lithium hydride products are as follows Figure 2 The presence of characteristic peaks belonging to lithium hydride indicates that the obtained lithium hydride has high crystallinity and that the hydrogenation of lithium metal is relatively complete.
[0073] Example 2
[0074] In an argon-protected glove box, 1.5g of lithium granules and pyridine (by mass) were weighed and placed into a 200ml stainless steel ball mill jar at a ratio of 1:0.3. Stainless steel balls with a diameter of 15mm were placed inside. Hydrogen gas at 2MPa was introduced through a valve at the top of the ball mill jar, and ball milling was performed under this pressure. The milling conditions were: ball-to-material ratio 60:1, room temperature, rotation speed 200 rpm, a 1-minute break after every 5 minutes of milling, and hydrogen replenishment every 5 hours of milling. This process was repeated for 10 hours to obtain lithium hydride product.
[0075] Characterization:
[0076] The appearance of the lithium hydride product obtained by ball milling is as follows Figure 3 As can be seen, the lithium hydride product is a white powder with no metallic luster, indicating that the lithium metal is completely hydrogenated.
[0077] XRD results of lithium hydride products are as follows Figure 4 The presence of characteristic peaks belonging to lithium hydride indicates that the obtained lithium hydride has high crystallinity and that the hydrogenation of lithium metal is relatively complete.
[0078] Example 3
[0079] In an argon-protected glove box, 1g of sodium and cyclohexane were weighed in a 1:0.3 ratio and placed into a 200ml stainless steel ball mill jar, which contained 15mm diameter stainless steel balls. Hydrogen gas at 3MPa was introduced through a valve at the top of the jar, and the ball was milled under this pressure. The milling conditions were: ball-to-material ratio 80:1, room temperature, 200 rpm, a 1-minute break after every 5 minutes of milling, and hydrogen replenishment every 5 hours. This process was repeated for 30 hours. The sample was then calcined at 300℃ for 3 hours under 10bar hydrogen pressure to obtain a highly crystalline sodium hydride product.
[0080] The sodium hydride product obtained by ball milling has the following appearance: Figure 5 As can be seen, the sodium hydride product is a grayish-white powder without metallic luster, indicating that the sodium metal is completely hydrogenated.
[0081] Example 4
[0082] In an argon-protected glove box, 1g of lithium granules and 1g of benzene were weighed at a mass ratio of 1:0.2 and placed into a 200ml stainless steel ball mill jar containing 15mm diameter stainless steel balls. Hydrogen gas at 2MPa was introduced through a valve at the top of the ball mill jar, and ball milling was performed under this pressure. The milling conditions were: ball-to-material ratio 110:1, room temperature, rotation speed 200 rpm, a 1-minute break after every 5 minutes of milling, and hydrogen replenishment every 5 hours. This process was repeated for 15 hours. The sample was then calcined at 300℃ for 3 hours under a hydrogen pressure of 5 bar to obtain a highly crystalline lithium hydride product.
[0083] Example 5
[0084] In an argon-protected glove box, 1g of sodium and formaldehyde (by mass) were weighed and placed into a 200ml stainless steel ball mill jar at a ratio of 1:0.2. Stainless steel balls with a diameter of 15mm were placed inside. Hydrogen gas at 3MPa was introduced through a valve at the top of the jar, and ball milling was performed under this pressure. The milling conditions were: ball-to-material ratio 110:1, room temperature, rotation speed 200 rpm, a one-minute break after every five minutes of milling, and hydrogen replenishment every five hours. This process was repeated for 15 hours. The sample was then calcined at 200℃ for 3 hours under a hydrogen pressure of 20 bar to obtain a highly crystalline sodium hydride product.
[0085] Example 6
[0086] In an argon-protected glove box, 2g of lithium granules and methyl ethyl ketone were weighed at a mass ratio of 1:0.1 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 2MPa was introduced through a valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio 60:1, room temperature, rotation speed 200 rpm, a one-minute break after every five minutes of milling, and hydrogen replenishment every five hours. This process was repeated for 15 hours. The sample was then calcined at 300℃ for 3 hours under a hydrogen pressure of 5 bar to obtain a highly crystalline lithium hydride product.
[0087] Example 7
[0088] In an argon-protected glove box, 2g of lithium granules and ethyl acetate were weighed at a mass ratio of 1:0.4 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 3MPa was introduced through the gas valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio 80:1, room temperature, rotation speed 200 rpm, a one-minute break after every five minutes of ball milling, and hydrogen replenishment every five hours of ball milling. The process was repeated for 15 hours. The sample was then calcined at 200℃ for 3 hours under a hydrogen pressure of 4 bar to obtain a highly crystalline lithium hydride product.
[0089] Example 8
[0090] In an argon-protected glove box, 2g of sodium blocks and cyclohexanone were weighed at a mass ratio of 1:0.2 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 3MPa was introduced through the gas valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio of 90:1, room temperature, rotation speed of 250 rpm, a one-minute break after every five minutes of ball milling, and hydrogen replenishment every five hours of ball milling. The process was repeated for 15 hours. The sample was then calcined at 300℃ for 5 hours under a hydrogen pressure of 10 bar to obtain a highly crystalline sodium hydride product.
[0091] Example 9
[0092] In an argon-protected glove box, 2g of lithium granules and methyl ethyl ketone were weighed at a mass ratio of 1:0.2 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. The ball milling conditions were: ball-to-material ratio of 80:1, room temperature, rotation speed of 200 rpm, with a 5-minute milling interval followed by a 1-minute rest, and repeated milling for 15 hours. It was found that when organic solvent was present but no hydrogen was present, the alkali metal did not agglomerate during the ball milling process, resulting in a fine lithium metal powder product.
[0093] The appearance of the comparative sample obtained in Example 9 is as follows: Figure 8 ,from Figure 8 The results show that the ball-milled product is a metallic powder without metallic luster, indicating that the lithium particles were significantly refined after ball milling.
[0094] Comparative Example 1
[0095] In an argon-protected glove box, 2g of lithium granules were weighed and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 3MPa was introduced through the gas valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio 80:1, room temperature, rotation speed 200 rpm, a one-minute break after every five minutes of ball milling, and hydrogen replenishment every five hours of ball milling. The process was repeated for 15 hours. It was found that alkali metals agglomerated during the ball milling process when no organic solvent was present.
[0096] The appearance of the comparative sample obtained in Comparative Example 1 is as follows Figure 6 The comparison sample still had a noticeable metallic luster, indicating that the lithium metal did not react.
[0097] XRD patterns of the comparison samples are as follows Figure 7 The obvious diffraction peaks belonging to lithium can be seen, indicating that the metallic lithium did not undergo a hydrogenation reaction.
[0098] Comparative Example 2
[0099] In an argon-protected glove box, 2g of lithium granules and furan were weighed at a mass ratio of 1:0.2 and placed into a 200ml stainless steel ball mill jar, which contained stainless steel balls with a diameter of 15mm. Hydrogen gas at 3MPa was introduced through the gas valve at the top of the ball mill jar, and ball milling was performed under this pressure. The ball milling conditions were: ball-to-material ratio 80:1, room temperature, rotation speed 200 rpm, a one-minute break after every five minutes of ball milling, and hydrogen replenishment every five hours of ball milling. The process was repeated for 15 hours. It was found that when furan was present as a reactant, the alkali metal could not be hydrogenated during the ball milling process.
[0100] The appearance of the comparative sample obtained in Comparative Example 2 is as follows Figure 9 The comparison sample was still a lithium metal sheet with a distinct metallic luster, indicating that the hydrogenation reaction of lithium metal could not proceed when the organic solvent was furan.
[0101] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing an alkali metal hydride, characterized in that, The preparation method includes at least: Under an inactive atmosphere, a raw material containing alkali metal, organic solvent, and hydrogen is ball-milled to obtain the alkali metal hydride. The alkali metal is selected from at least one of Li and Na; The organic solvent is selected from at least one of cyclohexane, isoprene, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, dimethyl ether, diethyl ether, trimethylamine, dimethylamine, methylamine, triethylamine, diethylamine, dimethylethanolamine, methyl diethanolamine, methanol, ethanol, butanol, methylcyclopentenolone, methanethiol, ethanethiol, ethylenedithiol, 1-propanethiol, ethyl formate, ethyl propionate, and methyl acetate.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the alkali metal to the organic solvent is 1:0.1 to 1:
1.
3. The preparation method according to claim 1, characterized in that, The partial pressure of the hydrogen gas is 0.1 MPa to 10 MPa.
4. The preparation method according to claim 1, characterized in that, The ball milling time is 1~60 h, and the ball milling temperature is 0~100 ℃.
5. The preparation method according to claim 1, characterized in that, The ball milling time is 8-15 h, and the ball milling temperature is 15-60 ℃.
6. The preparation method according to claim 1, characterized in that, The mass ratio of the media balls to the raw materials during the ball milling process is 20:1 to 120:
1.
7. The preparation method according to claim 1, characterized in that, The ball milling includes ball milling on a planetary ball mill, a horizontal ball mill, or a vibratory ball mill.
8. The preparation method according to claim 7, characterized in that, The planetary ball mill rotates at a speed of 50-600 rpm.
9. The preparation method according to claim 7, characterized in that, The horizontal ball mill has a rotational speed of 50~300 rpm.
10. The preparation method according to claim 7, characterized in that, The vibration ball mill has a rotation speed of 10~100 rpm and an excitation frequency of 500~2000 times / min.
11. The preparation method according to claim 1, characterized in that, The inactive atmosphere is selected from at least one of helium atmosphere, neon atmosphere, argon atmosphere, krypton atmosphere, and xenon atmosphere.
12. The preparation method according to claim 1, characterized in that, The ball milling process also includes at least one of calcination, purging, and vacuuming.
13. The preparation method according to claim 12, characterized in that, The calcination atmosphere is hydrogen, the hydrogen back pressure is 0.1~3MPa, the calcination temperature is 100~400℃, and the calcination time is 0.5~20h.
14. The preparation method according to claim 12, characterized in that, The purging gas is selected from at least one of hydrogen, helium, neon, argon, krypton, and xenon.
15. The preparation method according to claim 12, characterized in that, The vacuum level of the vacuum pump is less than 0.01 bar.