Composite hydrogen storage material, and preparation method and application thereof

Abstract

The application discloses a kind of composite hydrogen storage materials and its preparation method and application, belong to hydrogen storage material and its preparation technical field.The application solves the problems such as excessive amount of additive in existing aluminum hydride composite hydrogen storage system and poor low-temperature kinetics.The application uses rare earth nitride as additive, uses the multi-valence characteristics of rare earth element as active center, and uses the attraction of negative hydrogen by nitrogen element to accelerate hydrogen dissociation and transmission, and because nitrogen element has abundant valence, rare earth element can be used as bridge with aluminum hydride through nitrogen active site to realize the synergistic effect between them, the affinity of rare earth element and hydrogen element is enhanced by the electron-donating effect of nitrogen element, the dehydrogenation temperature of aluminum hydride material is reduced, and the dehydrogenation kinetics of aluminum hydride material in low-temperature region is also improved.In addition, the preparation process of the composite hydrogen storage material provided by the application is simple and mature, and the raw materials are cheap and easy to obtain, which is convenient for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite hydrogen storage material, a preparation method and application thereof, and belongs to the technical field of hydrogen storage materials and preparation thereof. BACKGROUND

[0002] Solid light metal hydrides have high hydrogen storage density, mild dehydrogenation conditions, high safety, and high purity of hydrogen gas, and can be directly used as a direct hydrogen source for portable hydrogen fuel cells, and are one of the most potential hydrogen storage materials.

[0003] For example, aluminum hydride (AlH3) has ultra-high hydrogen storage capacity (~10.1wt%) and moderate dehydrogenation temperature (~140℃), and is very suitable as a portable hydrogen storage tank content material. However, considering the working temperature range of the fuel cell and the unnecessary weight problem caused by the heat exchange system, the dehydrogenation temperature of the aluminum hydride hydrogen storage system still needs to be further reduced, and the dehydrogenation kinetics in the low temperature range needs to be improved. Therefore, optimizing light metal hydrides and constructing a new type of composite hydrogen storage material that meets actual needs is a difficult problem that needs to be overcome in the current technical field.

[0004] Related research on optimizing aluminum hydride by adding rare earth oxide additives in the prior art has made some progress, but the capacity of the composite product is generally lower than 9wt%. SUMMARY

[0005] In order to solve the problems of excessive amount of additives and poor low-temperature kinetics in the existing aluminum hydride composite hydrogen storage system, the present application provides a composite hydrogen storage material, a preparation method and application thereof.

[0006] The technical scheme of the present application is as follows:

[0007] One of the purposes of the present application is to provide a composite hydrogen storage material, which is composed of aluminum hydride powder and lanthanum nitride particles.

[0008] Further limited, the mass percentage of lanthanum nitride particles in the composite hydrogen storage material is 1-10%.

[0009] Further limited, the mass percentage of lanthanum nitride particles in the composite hydrogen storage material is 5%.

[0010] The second purpose of the present application is to provide a preparation method of the above-mentioned composite hydrogen storage material, which specifically mixes aluminum hydride powder and lanthanum nitride particles, and performs multiple ball milling treatments under a protective atmosphere to obtain a composite hydrogen storage material.

[0011] Further limited, the size of the lanthanum nitride particles is 1-10μm.

[0012] Further limited, the rotation speed of the ball milling treatment is 350rpm.

[0013] Further limited, the ball milling processing ball material ratio is 50:1.

[0014] Further limited, the ball milling processing times is 4 times.

[0015] Further limited, the single ball milling time is 15 min, and after the single ball milling is completed, it is stopped for 10 min, and the next ball milling processing is carried out after changing the rotation direction of the ball milling disc.

[0016] Further limited, the protective atmosphere is argon.

[0017] The present application has the beneficial effects:

[0018] (1) The present application uses rare earth nitride as an additive, uses the multi-valence characteristics of rare earth elements as an active center, and uses the attraction of nitrogen elements to negative hydrogen to accelerate the dissociation and transmission of hydrogen. At the same time, due to the rich valence of nitrogen elements, rare earth elements can be bridged with aluminum hydride through nitrogen active sites to realize the synergistic effect between the two, and the electron-donating effect of nitrogen elements enhances the affinity of rare earth elements and hydrogen elements, reduces the dehydrogenation temperature of aluminum hydride material, and improves the dehydrogenation kinetics of aluminum hydride material in the low temperature zone.

[0019] (2) The present application uses the synergistic effect of nitrogen elements and rare earth elements to reduce the amount of additives, thereby improving the capacity of the composite hydrogen storage material. Test results show that when the addition amount of lanthanum nitride is 5wt%, the initial dehydrogenation temperature of the composite material is reduced to 80℃, the capacity reaches 9.2wt%, and the effective hydrogen storage capacity at 100℃, 2h is more than 7.0wt%.

[0020] (3) The present application uses the synergistic effect of nitrogen elements and rare earth elements to obtain excellent catalytic activity, so the ball milling processing time is only 1h, which reduces the initial hydrogen release temperature of aluminum hydride hydrogen storage material from 145℃ to below 85℃, and the capacity loss during ball milling is only 0.37wt%, and the capacity retention rate is 96%.

[0021] (4) The preparation process of the composite hydrogen storage material provided by the present application is simple, mature and stable, and the raw materials are cheap and easy to obtain, which is suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The comparison chart of the temperature-controlled dehydrogenation curves of the composite hydrogen storage materials prepared in Examples 1~2 and Comparative Example 1 and the original aluminum hydride;

[0023] Figure 2 The comparison chart of the differential curves of the temperature-controlled dehydrogenation curves of the composite hydrogen storage materials prepared in Examples 1~2 and Comparative Example 1 and the original aluminum hydride;

[0024] Figure 3The dehydrogenation curve of the composite hydrogen storage material prepared in Example 1~2 and Comparative Example 1 at 100℃ compared with the original aluminum hydride;

[0025] Figure 4 The N 1s orbit XPS spectrum of the composite hydrogen storage material prepared in Example 2 before dehydrogenation;

[0026] Figure 5 The N 1s orbit XPS spectrum of the composite hydrogen storage material prepared in Example 2 after dehydrogenation. DETAILED DESCRIPTION

[0027] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0028] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art unless otherwise specified, which can be obtained by commercial channels by those skilled in the art.

[0029] Example 1

[0030] 0.570g of aluminum hydride powder and 0.030g of commercially available lanthanum nitride particle sample (particle size of 1~10μm) were weighed respectively and uniformly mixed in an argon atmosphere, with a total mass of 0.6g. Then the uniformly mixed sample was loaded into a ball mill jar, and stainless steel balls (total mass of 30g) were added to the ball mill jar according to the ball-to-material ratio of 50:1. The ball mill jar was sealed in an argon atmosphere, and the sealed ball mill jar was placed in a planetary ball mill for mechanical ball milling. The rotation speed of the ball mill was 350rpm, and the ball milling time was 1h. In order to prevent the decomposition of aluminum hydride caused by high temperature of the jar, the ball milling time was divided into four equal parts, each for 15min, and the rotation direction of the planetary ball mill disc was changed every 10min between two parts. After the ball milling process was completed, the ball mill jar was taken out and opened in an argon atmosphere, and the lanthanum nitride-aluminum hydride composite hydrogen storage material product was collected and named as LaN-0.05.

[0031] Example 2

[0032] 0.552 g of aluminum hydride powder and 0.048 g of lanthanum nitride sample (particle size of 1-10 μm) were weighed respectively and mixed uniformly in an argon atmosphere, with a total mass of 0.6 g. Then the uniformly mixed sample was loaded into a ball mill jar, and stainless steel balls (total mass of 30 g) were added to the ball mill jar according to a ball-to-material ratio of 50:1. The ball mill jar was sealed in an argon atmosphere, and the sealed ball mill jar was placed in a planetary ball mill for mechanical milling. The rotation speed of the ball mill was 350 rpm, and the ball milling time was 1 h. To prevent the aluminum hydride from being decomposed by heat due to a high temperature of the jar, the ball milling time was equally divided into four segments, each for 15 min, and the rotation direction of the planetary ball mill disc was changed every 10 min between two segments. After the ball milling process was completed, the ball mill jar was taken out and opened in an argon atmosphere, and the lanthanum nitride-aluminum hydride composite hydrogen storage material product was collected, which was named as LaN-0.08.

[0033] Comparative Example 1

[0034] 0.6 g of aluminum hydride powder was weighed and loaded into a ball mill jar, and stainless steel balls (total mass of 30 g) were added to the ball mill jar according to a ball-to-material ratio of 50:1. The ball mill jar was sealed in an argon atmosphere, and the sealed ball mill jar was placed in a planetary ball mill for mechanical milling. The rotation speed of the ball mill was 350 rpm, and the ball milling time was 1 h. To prevent the aluminum hydride from being decomposed by heat due to a high temperature of the jar, the ball milling time was equally divided into four segments, each for 15 min, and the rotation direction of the planetary ball mill disc was changed every 10 min between two segments. After the ball milling process was completed, the ball mill jar was taken out and opened in an argon atmosphere, and the nanosized aluminum hydride powder was collected, which was named as B.M. AlH3.

[0035] Effect Example

[0036] (1) The composite hydrogen storage materials prepared in Examples 1-2 and Comparative Example 1 and the aluminum hydride powder were subjected to temperature-controlled dehydrogenation tests and constant-temperature dehydrogenation tests at 100°C, and the corresponding dehydrogenation amounts were calibrated. The specific temperature-controlled dehydrogenation test was a constant-rate heating, with a heating rate of 2°C / min, and the initial dehydrogenation temperature calibrated was the zero-point temperature at which y in the differential curve of the temperature-controlled dehydrogenation curve was greater than 0 (affected by the test conditions, this temperature was used as a reference and comparison, and did not represent that the hydrogen storage material did not completely dehydrogenate below this temperature). In addition, considering the actual working time of the portable tank, the dehydrogenation capacity within 2 h was selected as the effective capacity of the constant-temperature dehydrogenation at 100°C.

[0037] The test results are shown in Table 1. Figures 1-3As shown, the comprehensive analysis shows that the initial dehydrogenation temperature of the aluminum hydride powder is 145℃, the total dehydrogenation amount is 10.0wt%, the effective dehydrogenation amount at 100℃ for 2h is 0.08wt%, and no dehydrogenation occurs at 80℃. The initial dehydrogenation temperature of the B.M. AlH3 prepared in the comparative example 1 is 109℃, the total dehydrogenation amount is 9.93wt%, and the effective dehydrogenation amount at 100℃ for 2h is 3wt%. The initial dehydrogenation temperature of the LaN-0.05 composite hydrogen storage material prepared in the example 1 is 78℃, which is reduced by about 67℃ compared with the aluminum hydride powder, and the total dehydrogenation amount can reach 9.24wt%, and the effective dehydrogenation amount at 100℃ for 2h reaches 7.08wt%. The initial dehydrogenation temperature of the LaN-0.08 composite hydrogen storage material prepared in the example 2 is 82℃, the total dehydrogenation amount can reach 9.03wt%, and the effective dehydrogenation amount at 100℃ for 2h is 6.86wt%.

[0038] (2) The X-ray photoelectron spectroscopy analysis of the composite hydrogen storage material prepared in the example 2 before and after dehydrogenation is further carried out, and the test results are shown in Figure 4 and 5 As can be known from the analysis of the surface electronic state of the elements by XPS, the nitrogen element participates in the electron transfer process. This process is divided into two parts. Firstly, the electron concentration of hydrogen is increased due to the electron absorption effect between the nitrogen element and the negative hydrogen, and the reducing property is enhanced, which weakens the Al-H bond. This effect has a synergistic effect with the "hydrogen pump" effect of the rare earth element, which can promote the dissociation and transmission of hydrogen at the same time, and effectively improve the catalyst activity. Secondly, it plays a bridge role in the electron transfer, and communicates the electron exchange process between the rare earth element and the metal center, and improves the electron exchange efficiency. In summary, the nitrogen element has a relatively weak electron binding ability due to the weak electronegativity, and has a high electron activity, so it can play a relatively obvious role in improving the catalytic activity

[0039] As can be known from the above, the composite hydrogen storage material provided by the application utilizes the synergistic effect of the rare earth element and the nitrogen element, ensures the high capacity of the aluminum hydride, reduces the dehydrogenation temperature of the aluminum hydride material, and improves the dehydrogenation reaction kinetics of the aluminum hydride material, and realizes the low-temperature rapid dehydrogenation of the aluminum hydride material.

[0040] The above only describes the preferred embodiments of the present application, and the skilled in the art can make appropriate changes and modifications to the above embodiments, therefore, the present application is not limited to the above specific embodiments, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application.

Claims

1. A composite hydrogen storage material, characterized in that, It is composed of aluminum hydride powder and lanthanum nitride particles; The mass percentage of lanthanum nitride particles in the composite hydrogen storage material is 1-10%; the particle size of lanthanum nitride is 1-10 μm. Aluminum hydride powder and lanthanum nitride particles were mixed and subjected to multiple ball milling processes under a protective atmosphere to obtain a composite hydrogen storage material.

2. The composite hydrogen storage material according to claim 1, characterized in that, The mass percentage of lanthanum nitride particles in the composite hydrogen storage material is 5%.

3. A method for preparing the composite hydrogen storage material according to any one of claims 1 to 2, characterized in that, Aluminum hydride powder and lanthanum nitride particles were mixed and subjected to multiple ball milling processes under a protective atmosphere to obtain a composite hydrogen storage material.

4. The preparation method according to claim 3, characterized in that, Lanthanum nitride particles have a size of 1~10 μm.

5. The preparation method according to claim 3, characterized in that, The ball milling speed was 350 rpm.

6. The preparation method according to claim 3, characterized in that, The ball-to-material ratio for ball milling is 50:

1.

7. The preparation method according to claim 3, characterized in that, The ball milling process was performed four times.

8. The preparation method according to claim 3 or 7, characterized in that, The ball milling time is 15 minutes, and after each ball milling is completed, there is a 10-minute pause before the rotation direction of the ball milling disc is changed and the next ball milling process is carried out.

9. The preparation method according to claim 3, characterized in that, The protective atmosphere is argon.

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