Composite hydrogen storage material and preparation method thereof

Abstract

The invention provides a composite hydrogen storage material and a preparation method thereof. The preparation method comprises the steps that S1, magnesium raw material powder and lanthanum-nickel alloy raw material powder are subjected to plasma nanocrystallization treatment, and nanocrystallized magnesium powder and nanocrystallized lanthanum-nickel alloy powder are obtained; s2, the nanocrystallized magnesium powder and the nanocrystallized lanthanum-nickel alloy powder are mixed in an inert atmosphere, and mixed powder is obtained; adding a carbon source into the mixed powder to obtain a first material; performing first calcination on the first material to obtain a second material; and S3, performing secondary calcination on the second material to obtain the composite hydrogen storage material. The preparation process of the composite solid hydrogen storage material is designed, and the finally obtained composite hydrogen storage material has higher specific surface area, better tap density and finer particle size distribution through the procedures of plasma nanocrystallization, physical mixing, in-situ carbon coating surface modification, repeated calcination and the like; therefore, the hydrogen absorption and desorption rate is higher and the hydrogen storage capacity is larger in the hydrogen storage process.

Description

Technical Field

[0001] The present invention relates to the field of energy storage materials, and in particular, to a composite hydrogen storage material and a preparation method thereof. Background Art

[0002] As a clean secondary energy source with extremely high energy density, hydrogen energy is an ideal solution for storing and consuming fluctuating renewable energy such as photovoltaic and wind power, and avoiding the abandonment of light and wind. However, as a chemically active gas, hydrogen has more stringent requirements for storage and transportation during utilization. Existing hydrogen storage methods have many problems in terms of safety and economic benefits. Since the solid-state hydrogen storage method has high safety, low storage pressure, high hydrogen release purity, and convenient transportation, metal hydride hydrogen storage represented by magnesium has a high hydrogen storage mass density (the theoretical hydrogen storage density can reach 7.6 wt%), and is an ideal hydrogen storage material in the future.

[0003] Although magnesium-based solid-state hydrogen storage has significant advantages, it generally has problems such as poor reversibility and harsh hydrogen absorption and release conditions. This is mainly because the Mg-H chemical bond has strong ionic bond characteristics (reaction enthalpy ~75 kJ·mol -1 ), and hydrogen absorption is required at a relatively high temperature (300°C - 400°C) and hydrogen pressure (2.5 MPa - 40 MPa), and hydrogen release is required at a relatively high temperature (300°C - 400°C). In addition, the diffusion of H atoms in MgH2 is slow, which severely limits the hydrogen storage capacity and the hydrogen absorption and release rate of magnesium, becoming a bottleneck hindering its large-scale application. In addition, large-scale hydrogen storage also involves from microscopic material particles to macroscopic material aggregates, as well as the endothermic heat absorption during the hydrogen evolution process of the material and the exothermic heat release during the hydrogen release process. The application in hydrogen storage devices involves the control of heat transfer rate and uniformity, which seriously affects the practical application of the magnesium-based hydrogen storage and transportation system.

[0004] In view of the problems of high thermodynamic energy barrier and large kinetic resistance for hydrogen absorption and release of magnesium-based solid-state hydrogen storage materials, resulting in high hydrogen absorption and release temperature and slow rate, researchers have proposed a series of methods to modify the thermodynamic and kinetic properties of magnesium-based materials from aspects such as material composition, structure, surface properties, and functionalization, including nanosizing, alloying, hetero-composite, surface functionalization, catalytic synergy, etc., and certain results have been achieved in reducing the hydrogen absorption and release temperature of the material and improving the hydrogen absorption and release rate of the material. However, most methods are difficult to be scaled up or are costly, and are difficult to be applied to the large-scale industrial production of magnesium-based hydrogen storage materials. At present, only alloying and catalytic modification through mechanical ball milling process have been relatively widely applied in the research and small-batch preparation of magnesium-based hydrogen storage materials. However, due to the difficulty in directional design and fine regulation of the microscopic structure of the material, the material preparation process and performance control cannot be well coordinated with the mass transfer and heat transfer problems in its application in hydrogen storage devices, and a heat source at a relatively high temperature (≥200°C) is still required to assist hydrogen absorption or release, and the advantages of flexible, convenient and economic deployment and application of solid-state hydrogen storage cannot be realized.

[0005] For example, CN118308634A (a magnesium-based composite hydrogen storage material and its preparation method, CN202410426026.6) discloses a method for preparing a magnesium-based composite hydrogen storage material by mechanical alloying and two-step hydrogenation. Alloying elements nickel and niobium oxide catalyst are introduced through a ball milling process, and the magnesium-based composite hydrogen storage material is obtained through two-step hydrogenation. That is, the hydrogen absorption and desorption thermodynamics characteristics are regulated by introducing the transition metal Ni to form a magnesium-nickel alloy phase, and then the niobium oxide catalyst is introduced to control the alloy particle size, increase the hydrogenation reaction surface area, shorten the transmission path, and catalyze the dissociation of H2, thereby comprehensively promoting the hydrogenation process of the material. However, this solution is limited by the ball milling process, and indicators such as the product particle size cannot be effectively controlled. Its hydrogenation temperature is as high as 300 - 450 °C, the pressure is as high as 5 - 10 MPa, and the hydrogenation time is as long as 4 - 8 h, making it difficult to have the value of low-cost application.

[0006] CN117776101A (a solid-state magnesium-based hydrogen storage material MgH2-CrOOH@CNT and its preparation method, CN202311777851.2) discloses a method for modifying a magnesium-based hydrogen storage material with a carbon material-supported transition metal-based catalyst. The CrOOH@CNT catalyst is prepared by a hydrothermal reaction of a chromium source and carbon nanotubes CNT, and the obtained catalyst and MgH2 are mixed and ball milled under inert gas protection to obtain the solid-state magnesium-based hydrogen storage material MgH2-CrOOH@CNT. CN117463363A (a preparation method of a carbon cloth-supported nickel-palladium nanocatalyst and its application in solid-state hydrogen storage, CN202311502449.3) discloses a method for modifying a magnesium-based hydrogen storage material with a bimetallic catalyst. The carbon cloth is impregnated in a nickel-palladium bimetallic salt precursor solution, dried after impregnation, and the obtained carbon cloth is electrically treated in a protective atmosphere. While being electrically treated, rapid heat treatment and cooling are carried out in sequence to obtain a carbon cloth uniformly loaded with nickel-palladium nanocatalysts. The prepared carbon cloth-supported palladium-nickel nanocatalyst and magnesium hydride are mixed and ball milled in a protective atmosphere to form a composite hydrogen storage material. Both of these two technical solutions prepare composite hydrogen storage materials by developing new catalysts in combination with the ball milling process. Although the obtained materials can reduce the hydrogen absorption and desorption energy barriers of the magnesium-based hydrogen storage materials, a considerable amount of additional energy is still consumed during the preparation process of the materials, and their material properties and economic benefits still need to be improved.

[0007] Based on this, how to provide a preparation method that can optimize various physical and chemical properties from aspects such as the composition and microstructure design of solid-state hydrogen storage materials, so that the obtained composite hydrogen storage materials have more excellent hydrogen storage performance, is one of the important technical problems to be solved in this field. Summary of the Invention

[0008] The main object of the present invention is to provide a composite hydrogen storage material and a preparation method thereof, so as to solve the problem of poor hydrogen storage performance of the hydrogen storage materials in the prior art.

[0009] To achieve the above object, a first aspect of the present invention provides a preparation method of a composite hydrogen storage material, including: Step S1, performing plasma nanometerization treatment on magnesium raw material powder and lanthanum nickel alloy raw material powder respectively to obtain nanometerized magnesium powder and nanometerized lanthanum nickel alloy powder; Step S2, mixing the nanometerized magnesium powder and the nanometerized lanthanum nickel alloy powder in an inert atmosphere to obtain a mixed powder; adding a carbon source to the mixed powder to obtain a first material; the first material is calcined for the first time to obtain a second material; Step S3, the second material is calcined for the second time to obtain a composite hydrogen storage material.

[0010] Further, in Step S1, the plasma nanometerization treatment is carried out in a plasma nanometerization device, and the process of the plasma nanometerization treatment includes: turning on the power supply of the plasma nanometerization device, introducing medium gas through the medium gas inlet of the plasma nanometerization device, and the medium gas generates plasma in the plasma torch of the plasma nanometerization device; introducing sheath gas through the sheath gas inlet of the plasma nanometerization device; introducing cooling gas through the cooling gas inlet of the plasma nanometerization device; under the action of the feeding carrier gas, feeding the magnesium raw material powder or the lanthanum nickel alloy raw material powder into the plasma generator of the plasma nanometerization device at a feeding speed of 0.4 kg·h -1 ~1.5 kg·h -1 , and gasifying under the action of the plasma to obtain a material gas; the material gas enters the cooling chamber of the plasma nanometerization device and is cooled by the cooling gas to obtain nanometerized magnesium powder or nanometerized lanthanum nickel alloy powder.

[0011] Further, in Step S1, the flow rate of the feeding carrier gas is 0.25 m 3 ·h -1 ~1 m 3 ·h -1 ; and / or, the flow rate of the sheath gas is 3 m 3 ·h -1 ~6 m 3 ·h -1 ; and / or, the flow rate of the medium gas is 2 ± 0.2 m 3 ·h -1 , the voltage of the power supply is 8 ± 0.5 V, and the current is 7 ± 0.5 A.

[0012] Further, in Step S1, the flow rate of the cooling gas is 6 m 3 ·h -1 ~8 m 3 ·h -1 , and the pressure in the cooling chamber is 40 kPa to 60 kPa.

[0013] Further, in step S1, the particle size of the magnesium raw material powder is 50 mesh to 200 mesh, preferably 100 mesh to 150 mesh; the particle size of the lanthanum-nickel alloy raw material powder is 100 mesh to 350 mesh, preferably 200 mesh to 300 mesh.

[0014] Further, in step S2, the weight ratio of the nanosized magnesium powder to the nanosized lanthanum-nickel alloy powder is (3 - 19):1; and / or, the weight ratio of the total weight of the nanosized magnesium powder and the nanosized lanthanum-nickel alloy powder to the weight of the carbon source is (1 - 2):1; preferably, the carbon source is selected from one or more of asphalt powder, modified asphalt powder, and resin powder, and more preferably asphalt powder.

[0015] Further, in step S2, the heating rate of the first calcination is 1 °C / min to 5 °C / min, the holding temperature is 300 °C to 400 °C, and the holding time is 2 h to 3 h.

[0016] Further, in step S3, the heating rate of the second calcination is 2 °C / min to 5 °C / min, the holding temperature is 500 °C to 600 °C, and the holding time is 2 h to 3 h; preferably, the second calcination is carried out in a protective atmosphere, and more preferably the protective atmosphere is nitrogen and / or argon.

[0017] The second aspect of the present invention provides a composite hydrogen storage material, which is prepared by the preparation method of the above composite hydrogen storage material; the specific surface area of the composite hydrogen storage material is 20 m 2 ·g -1 ~70 m 2 ·g -1 ; and / or, the tapped density of the composite hydrogen storage material is 1.4 g·cm -3 ~1.7 g·cm -3 ; and / or, D10 of the composite hydrogen storage material is 3 μm to 6 μm, D50 is 6 μm to 10 μm, and D90 is 13 μm to 16 μm.

[0018] Further, the hydrogen absorption temperature of the composite hydrogen storage material is 60 °C to 180 °C at 2.5 MPa to 3.5 MPa; the hydrogen absorption capacity is 5 wt% to 7 wt%; the maximum hydrogen absorption rate is 0.70 wt% / min to 0.95 wt% / min; and / or, the hydrogen desorption temperature of the composite hydrogen storage material is 90 °C to 270 °C at 0.05 MPa to 0.15 MPa; the hydrogen desorption capacity is 4.5 wt% to 6.5 wt%; the maximum hydrogen desorption rate is 0.2 wt% / min to 0.5 wt% / min.

[0019] Applying the technical solution of the present invention, by designing the preparation process of the composite solid-state hydrogen storage material, through processes such as plasma nanonization, physical mixing, in-situ carbon coating surface modification, and multiple calcination, the finally obtained composite hydrogen storage material has a higher specific surface area, better tapped density, and finer particle size distribution, thus showing a faster hydrogen absorption and desorption rate and a larger hydrogen storage capacity during the hydrogen storage process. In addition, the preparation method provided by the present invention is simple to operate, the conditions are easy to control, and it is suitable for large-scale production, providing strong material support for the storage and application of hydrogen energy. Description of the Drawings

[0020] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 SEM characterization results of the composite hydrogen storage material obtained in Example 1, the scale bar in the figure is 2 μm;

[0022] Figure 2 SEM characterization results of the composite hydrogen storage material obtained in Example 1, the scale bar in the figure is 200 nm;

[0023] Figure 3 SEM characterization results of the composite hydrogen storage material obtained in Comparative Example 1, the scale bar in the figure is 2 μm. Detailed Description of the Embodiments

[0024] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0025] As described in the background art, the hydrogen storage materials in the prior art have the problem of poor hydrogen storage performance, that is, high hydrogen absorption / desorption temperature, small hydrogen absorption / desorption capacity, and slow hydrogen absorption / desorption rate. To solve the above technical problems, the first aspect of the present invention provides a preparation method of a composite hydrogen storage material, including: Step S1, respectively performing plasma nanonization treatment on the magnesium raw material powder and the lanthanum-nickel alloy raw material powder to obtain nanosized magnesium powder and nanosized lanthanum-nickel alloy powder; Step S2, mixing the nanosized magnesium powder and the nanosized lanthanum-nickel alloy powder in an inert atmosphere to obtain a mixed powder; adding a carbon source to the mixed powder to obtain a first material; the first material is calcined for the first time to obtain a second material; Step S3, the second material is calcined for the second time to obtain a composite hydrogen storage material.

[0026] By designing the preparation process of the composite solid-state hydrogen storage material, through plasma nanometrization treatment first, the activity of magnesium raw material powder and lanthanum nickel alloy (LaNi5) raw material powder is significantly improved. The obtained nanosized magnesium powder and nanosized lanthanum nickel alloy powder have a higher specific surface area, surface activity and shorter hydrogen transport path, thus improving the hydrogen storage performance of the composite hydrogen storage material. By introducing a carbon source, the thermal conductivity and stability of the material are enhanced. After two calcination treatments, secondary granulation of the nanosized magnesium powder and nanosized lanthanum nickel alloy powder is achieved, forming a micron-sized pomegranate fruit-like spherical structure with close contact. Finally, the obtained composite hydrogen storage material has a higher specific surface area, better tap density and more efficient hydrogen absorption and desorption thermodynamics and kinetics performance. Specifically:

[0027] (1) First, through the plasma nanometrization process, reduce the particle size of the high hydrogen storage capacity magnesium-based material, reduce the hydrogen transport path in the hydrogen storage carrier, and solve the problem of large kinetic resistance of hydrogen diffusion in the magnesium matrix phase.

[0028] (2) Drawing on the storage structure of "cache + memory" in computers, by mixing nanosized lanthanum nickel alloy powder into the nanosized magnesium powder, design a hierarchical hydrogen storage structure, and utilize the high-speed "cache" characteristics of mild hydrogen absorption and desorption conditions, small equilibrium pressure difference and fast hydrogen absorption and desorption rate to make up for the shortcomings of high hydrogen absorption and desorption reaction enthalpy, harsh temperature and pressure conditions, and slow hydrogen absorption and desorption rate of the magnesium-based material, and achieve high-capacity hydrogen storage at lower temperatures.

[0029] (3) By introducing a carbon source and calcining, a carbon-coated layer is formed and the nanosized magnesium powder and nanosized lanthanum nickel alloy powder are wrapped therein, improving the effective thermal conductivity of the nanosized magnesium powder and nanosized lanthanum nickel alloy powder, strengthening the macroscopic hydrogen absorption and desorption kinetic process of the obtained composite hydrogen storage material, and enhancing its thermal efficiency in the application of hydrogen storage devices. At the same time, the formed carbon layer has abundant pores, providing sufficient free transport channels for the hydrogen absorption and desorption process, and the carbon coating layer can effectively inhibit the particle agglomeration and pulverization caused by the change of the material unit cell volume during the hydrogen absorption and desorption process, realizing long-life hydrogen storage.

[0030] In particular, in the above preparation process, compared with other processes in the art that can nanometerize two raw material powders, the plasma nanometerization treatment can heat the two raw material powders to the vaporization state more rapidly, and then rapidly cool them in the cooling chamber to form spherical or near-spherical nanoscale particles. This process is faster and more efficient than traditional methods such as mechanical ball milling, which helps to form amorphous or semi-crystalline nanoscale particles, thus more significantly improving their reactivity. At the same time, the raw material particles of magnesium or lanthanum-nickel alloy rapidly vaporize and condense in a high-temperature and high-energy plasma environment, and the subsequently formed spherical nanoparticles generally have a lower tendency to agglomerate, enabling the two hydrogen storage active components to be uniformly mixed through a simple physical process. Moreover, during the plasma nanometerization treatment, the surfaces of the two metal powders can be preliminarily hydrogenated and activated by incorporating a small amount of hydrogen in a protective atmosphere, which helps the hydrogen absorption process of the resulting composite hydrogen storage material to occur during application, reduces its initial activation energy, and improves the hydrogen storage performance.

[0031] After obtaining the two nanometerized powders, in order to avoid the reaction of the activated surfaces after nanometerization and affect the hydrogen storage performance, they are mixed under inert conditions to obtain a mixed powder. In practical applications, the obtained nanometerized magnesium powder and nanometerized lanthanum-nickel alloy powder are first transferred to a glove box or a similar operating space protected by an inert atmosphere through a sealed collector. Then, a certain proportion of the two nanometerized powders is weighed and formulated, mixed, and further transferred to a nanomixer protected by an inert gas. After being processed at a certain rotation speed and direction for a period of time, a uniform mixed powder is obtained. Moreover, the preferred rotation speed for mixing is 30 ± 5 rpm, and it rotates forward for 5 ± 1 min first and then rotates backward for 5 ± 1 min to obtain the mixed powder.

[0032] After that, by introducing a carbon source and setting two calcination processes, the coating of the nanometerized magnesium powder and the nanometerized lanthanum-nickel alloy powder is achieved, thereby improving the thermal conductivity of the nanometerized magnesium powder and the nanometerized lanthanum-nickel alloy powder, promoting the heat transfer during the hydrogen absorption (endothermic) and hydrogen release (exothermic) processes of the finally obtained composite hydrogen storage material, and thus improving the hydrogen absorption and release rates. Moreover, the carbon coating layer can effectively inhibit the change in the unit cell volume of the metal or alloy material during the hydrogen absorption and release processes, prevent its agglomeration and pulverization, and extend the service life of the finally obtained composite hydrogen storage material. Among them, the first calcination is the in-situ polycondensation reaction of asphaltene rich in aromatic rings to coat the surface of the nanometerized magnesium powder and the nanometerized lanthanum-nickel alloy powder with carbon-containing organic matter. The continuous polycondensation of asphaltene further generates mesophase carbon microspheres containing the nanometerized magnesium powder and the nanometerized lanthanum-nickel alloy powder, forming a precursor with a structure similar to a pomegranate fruit. The second calcination completes the pyrolysis carbonization of the mesophase carbon to form the finished product of the composite hydrogen storage material.

[0033] In addition, the preparation method provided by the present invention is simple to operate, the conditions are easy to control, and it is suitable for large-scale production, providing strong material support for the storage and application of hydrogen energy.

[0034] In several typical embodiments, in step S1, the plasma nanonization treatment is carried out in a plasma nanonization device, and the process of the plasma nanonization treatment includes: turning on the power supply of the plasma nanonization device, introducing medium gas through the medium gas inlet of the plasma nanonization device, and generating plasma from the medium gas in the plasma torch of the plasma nanonization device; introducing sheath gas through the sheath gas inlet of the plasma nanonization device; introducing cooling gas through the cooling gas inlet of the plasma nanonization device; under the action of the feeding carrier gas, feeding magnesium raw material powder or lanthanum-nickel alloy raw material powder into the plasma generator of the plasma nanonization device at a feeding speed of 0.4 kg·h -1 ~1.5 kg·h -1 and vaporizing under the action of the plasma to obtain a material gas; the material gas enters the cooling chamber of the plasma nanonization device and is cooled by the cooling gas to obtain nanosized magnesium powder or nanosized lanthanum-nickel alloy powder. In a plasma environment, the two metal raw material powders are rapidly vaporized and cooled to form nanoparticles. And the feeding speed of 0.4 kg·h -1 ~1.5 kg·h -1 means that the magnesium raw material powder or lanthanum-nickel alloy raw material powder can be more fully heated and vaporized in the plasma environment, which helps to form smaller and more uniform nanoparticles. At the same time, the above feeding speed can promote the uniform dispersion of the two metal raw material powders in the plasma environment, thereby reducing the agglomeration phenomenon of nanoparticles that may occur during the cooling process, and further improving the performance of the obtained composite hydrogen storage material.

[0035] In step S1, further preferably, the flow rate of the feeding carrier gas is 0.25 m 3 ·h -1 ~0.75 m 3 ·h -1 . At the central position of the plasma torch, this flow rate of the feeding carrier gas can promote the two metal raw material powders to enter the plasma at a more appropriate rate and dispersion degree, reduce the excessive agglomeration of the raw materials, and at the same time also promote the formation of finer nanosized powder particles. And preferably, the flow rate of the sheath gas is 2 m 3 ·h -1 ~6 m 3 ·h -1 . On the one hand, it helps to stabilize the shape of the plasma torch, avoid the plasma directly contacting the reactor wall, and protect the equipment from high-temperature damage. On the other hand, this flow rate range of the sheath gas can control the external temperature of the plasma torch, so as to promote the two nanosized materials coming out of the plasma to be cooled more quickly, forming nanosized metal powders with more excellent hydrogen storage performance. Further preferably, the flow rate of the medium gas is 2 ± 0.2 m 3 ·h -1, the voltage of the power supply is 8 ± 0.5 V, and the current is 7 ± 0.5 A, so as to optimize the plasma environment, including temperature, pressure and chemical properties, so that the two metal raw material powders can be better gasified and cooled therein. Also, preferably, the flow rate of the cooling gas in step S1 is 6 m 3 ·h -1 ~8 m 3 ·h -1 , and the pressure in the cooling chamber is 40 kPa to 60 kPa. The above cooling conditions help to more quickly remove the heat from the environment around the plasma torch, promote the formation of amorphous particles, and then improve the hydrogen diffusion ability of the two nanosized powders and the finally obtained composite hydrogen storage material, and reduce the energy barrier during its hydrogen absorption and desorption process.

[0036] Generally speaking, through a large number of experiments, the inventors comprehensively considered and coordinately adjusted the parameters in the above plasma nanosizing process, and thus obtained two nanosized metal powders with good intrinsic hydrogen storage performance. The coordinated cooperation of the above parameters enables the obtained nanosized powders to more smoothly form a composite hydrogen storage material with a carbon layer coating with the carbon source, and finally show more excellent hydrogen storage capacity during application.

[0037] In order to better adapt to the above plasma nanosizing process, obtain nanosized metal powders with finer particle sizes, and then more significantly improve the comprehensive performance of the composite hydrogen storage material in which they are located, in several typical embodiments, the particle size of the magnesium raw material powder in step S1 is 50 mesh to 200 mesh; the particle size of the lanthanum-nickel alloy raw material powder is 100 mesh to 350 mesh. In several more typical embodiments, the particle size of the magnesium raw material powder in step S1 is 100 mesh to 150 mesh; the particle size of the lanthanum-nickel alloy raw material powder is 200 mesh to 300 mesh. The above-mentioned particle size ranges of the magnesium raw material powder and the lanthanum-nickel alloy raw material powder, which are further preferably selected, can not only respectively adapt to the plasma nanosizing process to obtain nanosized powders with excellent intrinsic hydrogen storage performance. More importantly, after nanosizing, they can better cooperate at the particle size level, improve the structural stability and overall consistency of the finally obtained composite hydrogen storage material, and then make it show higher hydrogen storage performance and service life.

[0038] Furthermore, it is preferable that the weight ratio of the nanostructured magnesium powder to the nanostructured lanthanum-nickel alloy powder in step S2 is (3-19):1. In the finally obtained composite hydrogen storage material, the nanostructured lanthanum-nickel alloy powder serves as a "cache", having mild hydrogen absorption and desorption conditions and a relatively fast reaction rate, while the nanostructured magnesium powder serves as a "large-capacity memory" with a high theoretical hydrogen storage capacity. Mixing the two according to the above weight relationship can find a better balance between high hydrogen storage capacity and fast hydrogen absorption and desorption rates, thereby enhancing the comprehensive hydrogen storage capacity of the obtained composite hydrogen storage material. At the same time, this weight ratio helps to form a uniformly distributed magnesium-lanthanum nickel composite structure in the finally obtained composite hydrogen storage material, forming a more stable and effective composite material, reducing the internal stress during the hydrogen absorption and desorption application process, inhibiting the pulverization phenomenon, and prolonging the cycle life.

[0039] Even further, through a large number of experiments, the inventor preferably selects the weight ratio of the total weight of the nanostructured magnesium powder and the nanostructured lanthanum-nickel alloy powder to the weight of the carbon source to be (1-2):1. The layered coating of the carbon source can not only improve the thermal conductivity of the material where it is located, promote heat transfer during hydrogen absorption and desorption, but also provide a channel for hydrogen transmission, improving the macroscopic hydrogen storage kinetics of the composite hydrogen storage material. And the dosage of the above carbon source can make the thickness of the formed carbon coating layer moderate, neither sacrificing too much hydrogen storage capacity nor significantly enhancing the thermal stability and hydrogen absorption and desorption rate of the finally obtained composite hydrogen storage material.

[0040] In several typical embodiments, the carbon source is selected from one or more of asphalt powder, modified asphalt powder, and resin powder. The resin powder can specifically be phenolic resin powder. Among the above carbon source types, especially asphalt powder, which contains rich aromatic rings, can undergo an in-situ polycondensation reaction during the two calcination processes, coating the surface of the nanostructured magnesium powder and the nanostructured lanthanum-nickel alloy powder with carbon-containing organic matter, and aggregating carbon to form micron-sized particles with a more stable structure and better hydrogen storage performance.

[0041] In several more typical embodiments, the particle size of the asphalt powder used in the present invention is 100 mesh to 200 mesh, and the softening temperature is 200 °C to 280 °C. Moreover, in the asphalt powder, the asphalt mesophase substances can be classified into α, β, and γ resins according to molecular weight. Among them, β resin, compared with α and γ resins, has a moderate molecular weight and viscosity and a stronger π-electron conjugate system, and can form a more ordered graphite-like microcrystalline structure. Based on this, the inventor preferably uses β resin content in the asphalt powder ≥ 35 wt%, so that the asphalt pyrolytic carbon product has higher thermal conductivity and mechanical strength, thereby obtaining a composite hydrogen storage material with higher comprehensive performance. Moreover, for the modified asphalt powder, it is preferably the asphalt powder modified by phenolic resin, and the incorporation ratio of phenolic resin is 20% to 30%. Phenolic resin is a polymer formed by the reaction of phenols and formaldehyde, and its molecular structure contains a large number of aromatic rings and ether bonds. Using the asphalt powder modified by phenolic resin can form a carbon layer with a higher elastic modulus during the calcination process, thereby further optimizing the microstructure of the obtained hydrogen storage material.

[0042] Furthermore, for the first calcination in step S2, through a large number of experiments, the inventor preferably uses a heating rate of 1 °C / min to 5 °C / min, a holding temperature of 300 °C to 400 °C, and a holding time of 2 h to 3 h. First of all, this heating rate can prompt the reaction system to gradually reach and stabilize at the required calcination temperature, that is, to make the internal and surface temperatures rise evenly, reduce thermal stress, and is conducive to forming a composite hydrogen storage material with a more stable microstructure. And the above-mentioned holding temperature and time can make the carbon source more fully wrap the nano-sized magnesium powder and nano-sized lanthanum nickel alloy powder, form a more uniform reaction system to be reacted, and then promote the formation of a more uniformly wrapped carbon layer during the subsequent calcination process, and ultimately more significantly enhance the hydrogen storage capacity of the obtained composite hydrogen storage material.

[0043] In practical applications, it is preferably carried out under stirring conditions for the first calcination, and the stirring speed is 100 ± 20 rpm. Under the condition of maintaining stirring, heating the reactor kettle body for carbon coating, that is, the first calcination, to the temperature of the first calcination and holding heat at the above speed can make the carbon source more effectively coat the nano-sized magnesium powder and nano-sized lanthanum nickel alloy powder, and then is conducive to the subsequent in-situ formation of a carbon layer with a wrapping effect, forming a composite hydrogen storage material precursor with a structure similar to a pomegranate fruit, and finally obtaining a composite hydrogen storage material with better hydrogen storage performance after the second calcination.

[0044] In practical applications, in order to obtain a composite hydrogen storage material with less impurities, more stable structure and better comprehensive performance, after the carbon-coated reactor used in the first calcination is cooled to room temperature and before the second calcination, step S3 further includes crushing the second material, that is, the reaction mixture after carbon coating and secondary granulation, so that the particle size of the second material is 100-400 mesh. Then, it is transferred to a leaching separator and washed multiple times with an organic solvent (the instrument used for washing can be a standard Soxhlet extractor or an asphalt extractor) to remove the unreacted carbon source raw materials and reaction by-products, and then an air stream is passed through to dry and crush it to obtain a pure magnesium-lanthanum nickel-carbon composite material precursor.

[0045] The magnesium-lanthanum nickel-carbon composite material precursor obtained by the first calcination, that is, the second material, after the second calcination, the carbon matrix in which two kinds of nano-sized metal powders are dispersed undergoes further carbonization and forms a carbon layer to wrap the nano-sized metal powder particles. During this process, the inventors preferably select the heating rate to be 2 °C / min to 5 °C / min, the holding temperature to be 500 °C to 600 °C, and the holding time to be 2 h to 3 h through a large number of experiments. Under these conditions, the second calcination can promote the more complete conversion of the carbon source into the carbon layer and inhibit the excessive sintering or grain boundary growth of the two metals during the calcination process. At the same time, under these calcination conditions, the binding between the nano-particles of magnesium and lanthanum nickel alloy and the carbon layer is tighter, thereby increasing the packing density of the obtained composite hydrogen storage material, optimizing the storage and transmission capacity of hydrogen, and achieving a more effective compatibility between the hydrogen storage capacity and efficiency. In several typical embodiments, in order to reduce impurities, improve the structural stability of the obtained composite hydrogen storage material and extend its service life, it is preferred that the second calcination is carried out in a protective atmosphere, and more preferably the protective atmosphere is nitrogen and / or argon.

[0046] The second aspect of the present invention provides a composite hydrogen storage material, which is prepared by the preparation method of the above composite hydrogen storage material. The obtained composite hydrogen storage material has high activity, high specific surface area and remarkable hydrogen storage performance. It should be particularly noted that due to the particularity of the material field and the limitations of existing testing and characterization means, it is difficult to comprehensively and quantitatively characterize the complex microstructure of the above-obtained composite hydrogen storage material, but the performance test results show that the composite hydrogen storage material obtained in this application has more excellent physical and chemical characteristics, so that it can exhibit particularly superior hydrogen storage performance.

[0047] In several preferred embodiments, the specific surface area of the composite hydrogen storage material is 20 m 2 ·g -1 ~70 m 2 ·g -1 , more preferably 50 m 2 ·g -1 ~70 m 2 ·g -1A high specific surface area can provide more hydrogen storage sites, improving the hydrogen storage capacity and the hydrogen absorption and desorption rates of the composite hydrogen storage material. Further, the tapped density of the composite hydrogen storage material is 1.4 g·cm -3 ~1.7 g·cm -3 . Compared with hydrogen storage functional materials with higher particle sizes, the composite hydrogen storage material provided by the present invention still has a relatively high tapped density under the conditions of significantly reduced particle size and significantly increased specific surface area, thereby being able to effectively improve the filling efficiency of the material and having higher application value. Further preferably, the D10 of the composite hydrogen storage material is 3 μm to 6 μm, the D50 is 6 μm to 10 μm, and the D90 is 13 μm to 16 μm. The composite hydrogen storage material prepared by the present invention has a lower particle size, and such a fine particle size distribution can further improve the hydrogen absorption and desorption performance of the composite hydrogen storage material, reduce the pressure loss during hydrogen storage, and have higher hydrogen storage performance.

[0048] In several more preferred embodiments, the hydrogen absorption temperature of the composite hydrogen storage material is 60°C to 180°C at 2.5 MPa to 3.5 MPa (preferably the actual test condition is 3 MPa); the hydrogen absorption capacity is 5 wt% to 7 wt%; the maximum hydrogen absorption rate is 0.70 wt% / min to 0.95 wt% / min; the maximum hydrogen absorption rate is 0.72 wt% / min to 0.91 wt% / min; and / or, the hydrogen desorption temperature of the composite hydrogen storage material is 90°C to 270°C at 0.05 MPa to 0.15 MPa (preferably the actual test condition is 0.1 MPa); the hydrogen desorption capacity is 4.5 wt% to 6.5 wt%; the maximum hydrogen desorption rate is 0.2 wt% / min to 0.5 wt% / min. That is to say, the obtained composite hydrogen storage material has excellent hydrogen storage performance, showing lower hydrogen absorption / desorption temperatures, larger hydrogen absorption / desorption capacities, and faster maximum hydrogen absorption / desorption rates.

[0049] The following further describes the present application in detail with specific embodiments, which should not be construed as limiting the scope claimed by the present application.

[0050] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0051] Example 1

[0052] A preparation method of a composite hydrogen storage material:

[0053] (1) Set the operating parameters of the plasma nanonization device, including the gas flow rates (feed carrier gas, middle gas, sheath gas, cooling gas), power input (voltage, current), vacuum degree, and cooling chamber pressure. After fully replacing the device with the working gas argon and reaching the set vacuum degree, start the plasma torch and wait for it to operate stably for more than 10 minutes. Among them, set the flow rate of the feed carrier gas to 0.5 m 3 ·h -1 , the flow rate of the middle gas to 2 m 3 ·h -1 , the flow rate of the sheath gas to 4 m 3 ·h -1 , the flow rate of the cooling gas to 6 m 3 ·h -1 ; set the voltage of the power supply to 8.5 kV and the current to 7.5 A; set the cooling chamber pressure to 60 kPa. Under the action of the feed carrier gas, feed the magnesium raw material powder with a particle size of 100 mesh into the plasma generator of the plasma nanonization device at a feeding speed of 1 kg·h -1 , and obtain nanosized magnesium powder after gasification and condensation; similarly, under the action of the feed carrier gas, feed the lanthanum-nickel alloy raw material powder with a particle size of 200 mesh into the plasma generator of the plasma nanonization device at a feeding speed of 0.5 kg·h -1 , and obtain nanosized lanthanum-nickel alloy powder after gasification and condensation.

[0054] (2) Transfer the obtained nanosized magnesium powder and nanosized lanthanum-nickel alloy powder to a glove box with inert atmosphere protection through a sealed collector. Weigh 950 g of nanosized magnesium powder and 50 g of nanosized lanthanum-nickel alloy powder (i.e., the weight ratio of nanosized magnesium powder to nanosized lanthanum-nickel alloy powder is 19:1), and mix the two in an argon-protected nano mixer at a rotation speed of 30 rpm for 10 minutes (5 minutes forward + 5 minutes reverse). Then transfer the mixed powder to the carbon-coated reactor kettle body, and add 1000 g of asphalt powder as the carbon source (at this time, the total weight of nanosized magnesium powder and nanosized lanthanum-nickel alloy powder and the weight of the carbon source ratio is 1:1). The asphalt powder used is high-temperature asphalt, with a particle size of 100 - 125 mesh, a softening temperature of 280 °C, and it contains 35% β-resin by mass fraction. Mix at a rotation speed of 100 rpm for 20 minutes to obtain the first material. Under the stirring condition of a rotation speed of 100 rpm, conduct the first calcination on the first material, and the heating rate of the first calcination is 2 °C / min, the holding temperature is 400 °C, and the holding time is 2 h. Then cool to room temperature to obtain the second material.

[0055] (3) The second material is crushed to 100 - 400 mesh and then transferred to a leaching separator. After that, using tetrahydrofuran as the solvent, the second material is leached until the filtrate is colorless and transparent, followed by air-blowing drying and dispersion to obtain a magnesium-lanthanum nickel-carbon composite material precursor. The dried and dispersed second material is transferred to a tube furnace and subjected to a second calcination in an argon atmosphere. The heating rate of the second calcination is 5 °C / min, the holding temperature is 600 °C, and the holding time is 2 h. Finally, a magnesium-lanthanum nickel-carbon composite hydrogen storage material is obtained.

[0056] The SEM characterization results of the obtained composite hydrogen storage material are shown in Figure 1 with a scale of 2 μm and Figure 2 .

[0057] Example 2

[0058] A preparation method of a composite hydrogen storage material:

[0059] (1) Set the operating parameters of the plasma nanosizing device, such as gas flow rate (including feed carrier gas, middle gas, sheath gas, cooling gas), power input (voltage, current), vacuum degree, and cooling chamber pressure. After fully displacing the device with the working gas argon and reaching the set vacuum degree, start the plasma torch and wait for it to operate stably for more than 10 min. Among them, set the flow rate of the feed carrier gas to 0.5 m 3 ·h -1 , the flow rate of the middle gas to 2.2 m 3 ·h -1 , the flow rate of the sheath gas to 4 m 3 ·h -1 , the flow rate of the cooling gas to 6 m 3 ·h -1 ; set the voltage of the power supply to 8.0 kV and the current to 7.5 A; set the cooling chamber pressure to 60 kPa. Under the action of the feed carrier gas, the magnesium raw material powder with a particle size of 150 mesh is fed into the plasma generator of the plasma nanosizing device at a feeding speed of 1 kg·h -1 , and after gasification and condensation, nanosized magnesium powder is obtained; similarly, under the action of the feed carrier gas, the lanthanum nickel alloy raw material powder with a particle size of 200 mesh is fed into the plasma generator of the plasma nanosizing device at a feeding speed of 0.5 kg·h -1 , and after gasification and condensation, nanosized lanthanum nickel alloy powder is obtained.

[0060] (2) Transfer the obtained nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder to a glove box protected by an inert atmosphere through a sealed collector. Weigh 900 g of nano-sized magnesium powder and 100 g of nano-sized lanthanum-nickel alloy powder (i.e., the weight ratio of nano-sized magnesium powder to nano-sized lanthanum-nickel alloy powder is 9:1), and mix the two in a nano mixer protected by argon at a rotation speed of 30 rpm for 10 min (5 min forward rotation + 5 min reverse rotation). Then transfer the mixed powder to the carbon-coated reactor kettle body, and add 1000 g of asphalt powder as the carbon source (at this time, the total weight of nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder to the weight of the carbon source is 1:1). The asphalt powder used is spinable asphalt, with a particle size of 150 - 200 mesh, a softening temperature of 200 °C, and containing 45% β-resin by mass fraction. Mix at a rotation speed of 100 rpm for 20 min to obtain the first material. Under the stirring condition with a rotation speed of 100 rpm, perform the first calcination on the first material, and the heating rate of the first calcination is 1 °C / min, the holding temperature is 300 °C, and the holding time is 3 h. Then cool to room temperature to obtain the second material.

[0061] (3) Crush the second material to 100 - 400 mesh and transfer it to a leaching separator. Then, using tetrahydrofuran as the solvent, leach the second material until the filtrate is colorless and transparent, and then perform air-blowing drying and dispersion to obtain the precursor of the magnesium-lanthanum-nickel-carbon composite material. Transfer the dried and dispersed second material to a tubular furnace and perform the second calcination in an argon atmosphere. The heating rate of the second calcination is 5 °C / min, the holding temperature is 600 °C, and the holding time is 2 h. Finally, obtain the magnesium-lanthanum-nickel-carbon composite hydrogen storage material.

[0062] Example 3

[0063] A preparation method of a composite hydrogen storage material:

[0064] (1) Set the operating parameters of the plasma nano-sizing device, such as gas flow rate (including feed carrier gas, middle gas, sheath gas, cooling gas), power input (voltage, current), vacuum degree, and cooling chamber pressure. After fully replacing the device with the working gas argon and reaching the set vacuum degree, start the plasma torch and wait for it to operate stably for more than 10 min. Among them, set the flow rate of the feed carrier gas to 0.5 m 3 ·h -1 , the flow rate of the middle gas to 1.8 m 3 ·h -1 , the flow rate of the sheath gas to 6 m 3 ·h -1 , and the flow rate of the cooling gas to 6 m 3 ·h -1; Set the voltage of the power supply to 8.5 kV and the current to 7.0 A; set the pressure in the cooling chamber to 40 kPa. Under the action of the feeding carrier gas, magnesium raw material powder with a particle size of 100 mesh is fed into the plasma generator of the plasma nanonization device at a feeding speed of 1 kg·h -1 and nano-sized magnesium powder is obtained after gasification and condensation; similarly, under the action of the feeding carrier gas, lanthanum-nickel alloy raw material powder with a particle size of 300 mesh is fed into the plasma generator of the plasma nanonization device at a feeding speed of 0.5 kg·h -1 and nano-sized lanthanum-nickel alloy powder is obtained after gasification and condensation.

[0065] (2) Transfer the obtained nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder to a glove box with inert gas protection through a sealed collector. Weigh 800 g of nano-sized magnesium powder and 200 g of nano-sized lanthanum-nickel alloy powder (i.e., the weight ratio of nano-sized magnesium powder to nano-sized lanthanum-nickel alloy powder is 4:1), and mix the two in a nano mixer under argon protection at a rotation speed of 30 rpm for 10 min (forward rotation for 5 min + reverse rotation for 5 min). Then transfer the mixed powder to the carbon-coated reactor kettle body, and add 1000 g of asphalt powder as the carbon source (at this time, the total weight of nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder and the weight of the carbon source ratio is 1:1). The asphalt powder used is high-temperature asphalt, its particle size is 125 - 150 mesh, the softening temperature is 250 °C, and it contains 40% β-resin by mass fraction. Mix at a rotation speed of 100 rpm for 20 min to obtain the first material. Under the stirring condition with a rotation speed of 100 rpm, perform the first calcination on the first material, and the heating rate of the first calcination is 5 °C / min, the holding temperature is 400 °C, and the holding time is 2 h. Then cool to room temperature to obtain the second material.

[0066] (3) Granulate the second material, that is, crush it to 100 mesh and transfer it to a leaching separator, then use tetrahydrofuran as the solvent to leach the second material until the filtrate is colorless and transparent, and then perform air-blowing drying and dispersion to obtain the precursor of the magnesium-lanthanum-nickel-carbon composite material. Transfer the dried and dispersed second material to a tubular furnace, and perform the second calcination in an argon atmosphere. The heating rate of the second calcination is 2 °C / min, the holding temperature is 550 °C, and the holding time is 2 h. Finally, obtain the magnesium-lanthanum-nickel-carbon composite hydrogen storage material.

[0067] Example 4

[0068] A preparation method of a composite hydrogen storage material:

[0069] (1) Set the operating parameters of the plasma nanosizing device, including gas flow rates (feed carrier gas, intermediate gas, sheath gas, cooling gas), power input (voltage, current), vacuum degree, and cooling chamber pressure. After fully purging the device with the working gas argon and reaching the set vacuum degree, start the plasma torch and wait for it to operate stably for more than 10 minutes. Among them, set the flow rate of the feed carrier gas to 0.25 m 3 ·h -1 , the flow rate of the intermediate gas to 2 m 3 ·h -1 , the flow rate of the sheath gas to 6 m 3 ·h -1 , the flow rate of the cooling gas to 8 m 3 ·h -1 ; set the voltage of the power supply to 8.5 kV and the current to 7.5 A; set the cooling chamber pressure to 50 kPa. Under the action of the feed carrier gas, feed the magnesium raw material powder with a particle size of 100 mesh into the plasma generator of the plasma nanosizing device at a feeding speed of 1.5 kg·h -1 , and obtain nanosized magnesium powder after gasification and condensation; similarly, under the action of the feed carrier gas, feed the lanthanum-nickel alloy raw material powder with a particle size of 200 mesh into the plasma generator of the plasma nanosizing device at a feeding speed of 0.8 kg·h -1 , and obtain nanosized lanthanum-nickel alloy powder after gasification and condensation.

[0070] (2) Transfer the obtained nanosized magnesium powder and nanosized lanthanum-nickel alloy powder to a glove box with inert atmosphere protection through a sealed collector. Weigh 750 g of nanosized magnesium powder and 250 g of nanosized lanthanum-nickel alloy powder (i.e., the weight ratio of nanosized magnesium powder to nanosized lanthanum-nickel alloy powder is 3:1), and mix the two in an argon-protected nano mixer at a rotation speed of 30 rpm for 10 minutes (5 minutes forward + 5 minutes reverse). Then transfer the mixed powder to the carbon-coated reactor kettle body, and add 750 g of asphalt powder as the carbon source (at this time, the total weight of nanosized magnesium powder and nanosized lanthanum-nickel alloy powder and the weight of the carbon source ratio is 4:3). The asphalt powder used is spinable asphalt, its particle size is 100 - 200 mesh, the softening temperature is 280 °C, and it contains 55% β-resin by mass fraction. Mix at a rotation speed of 100 rpm for 20 minutes to obtain the first material. Under the stirring condition of a rotation speed of 100 rpm, conduct the first calcination on the first material, and the heating rate of the first calcination is 5 °C / min, the holding temperature is 320 °C, and the holding time is 2 h. Then cool to room temperature to obtain the second material.

[0071] (3) Granulate the second material, that is, crush it to 100 mesh and transfer it to a leaching separator. Then, using tetrahydrofuran as a solvent, leach the second material until the filtrate is colorless and transparent, followed by air-blowing drying and dispersion to obtain a magnesium-lanthanum nickel-carbon composite material precursor. Transfer the dried and dispersed second material to a tube furnace and conduct the second calcination in an argon atmosphere. The heating rate of the second calcination is 2 °C / min, the holding temperature is 500 °C, and the holding time is 3 h. Finally, obtain the magnesium-lanthanum nickel-carbon composite hydrogen storage material.

[0072] Example 5

[0073] A preparation method of a composite hydrogen storage material:

[0074] (1) Set the operating parameters of the plasma nanonization device, such as gas flow rate (including feed carrier gas, middle gas, sheath gas, cooling gas), power input of the power supply (voltage, current), vacuum degree, and cooling chamber pressure. After fully replacing the device with the working gas argon and reaching the set vacuum degree, start the plasma torch and wait for it to operate stably for more than 10 min. Among them, set the flow rate of the feed carrier gas to 1.0 m 3 ·h -1 , the flow rate of the middle gas to 2 m 3 ·h -1 , the flow rate of the sheath gas to 6 m 3 ·h -1 , the flow rate of the cooling gas to 8 m 3 ·h -1 ; set the voltage of the power supply to 8.5 kV and the current to 7.5 A; set the cooling chamber pressure to 40 kPa. Under the action of the feed carrier gas, feed the magnesium raw material powder with a particle size of 100 mesh into the plasma generator of the plasma nanonization device at a feeding speed of 0.8 kg·h -1 , and obtain nanosized magnesium powder after gasification and condensation; similarly, under the action of the feed carrier gas, feed the lanthanum nickel alloy raw material powder with a particle size of 200 mesh into the plasma generator of the plasma nanonization device at a feeding speed of 0.4 kg·h -1 , and obtain nanosized lanthanum nickel alloy powder after gasification and condensation.

[0075] (2) Transfer the obtained nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder to a glove box with inert atmosphere protection through a sealed collector. Weigh 950 g of nano-sized magnesium powder and 50 g of nano-sized lanthanum-nickel alloy powder (i.e., the weight ratio of nano-sized magnesium powder to nano-sized lanthanum-nickel alloy powder is 19:1), and mix the two in a nano mixer under argon protection at a rotation speed of 30 rpm for 10 min (5 min forward + 5 min reverse). Then transfer the mixed powder to the carbon-coated reactor kettle body, and add 500 g of asphalt powder as the carbon source (at this time, the total weight of nano-sized magnesium powder and nano-sized lanthanum-nickel alloy powder to the weight of the carbon source is 2:1). The asphalt powder used is spinable asphalt, with a particle size of 150 - 200 mesh, a softening temperature of 250 °C, and containing 50% by mass of β resin. Mix at a rotation speed of 100 rpm for 20 min to obtain the first material. Under the stirring condition with a rotation speed of 100 rpm, perform the first calcination on the first material, and the heating rate of the first calcination is 2 °C / min, the holding temperature is 350 °C, and the holding time is 2 h. Then cool to room temperature to obtain the second material.

[0076] (3) Granulate the second material, that is, crush it to 100 mesh and transfer it to a leaching separator. Then, using tetrahydrofuran as the solvent, leach the second material until the filtrate is colorless and transparent, and then perform air drying and dispersion to obtain the precursor of the magnesium-lanthanum-nickel-carbon composite material. Transfer the dried and dispersed second material to a tubular furnace, and perform the second calcination in an argon atmosphere. The heating rate of the second calcination is 2 °C / min, the holding temperature is 600 °C, and the holding time is 2 h. Finally, obtain the magnesium-lanthanum-nickel-carbon composite hydrogen storage material.

[0077] Example 6

[0078] A preparation method of a composite hydrogen storage material:

[0079] The difference between this example and Example 1 is only that: an equal weight of modified asphalt powder is selected to replace the asphalt powder in step (2) as the carbon source. The modified asphalt powder used is phenolic resin modified asphalt powder, the incorporation ratio of phenolic resin is 20%, and the particle size of the modified asphalt powder is 100 - 125 mesh, the softening temperature is 260 °C, and the β resin content is 20 wt%.

[0080] Example 7

[0081] A preparation method of a composite hydrogen storage material:

[0082] The difference between this example and Example 1 is only that: an equal weight of resin powder is selected to replace the asphalt powder in step (2) as the carbon source. The resin powder used is linear phenolic resin with a residual carbon value of 54% - 58%, and the particle size is 100 - 125 mesh.

[0083] Comparative Example 1

[0084] Preparation method of a composite hydrogen storage material:

[0085] (1) Weigh 950 g of magnesium raw material powder with a particle size of 100 mesh and 50 g of lanthanum-nickel alloy raw material powder with a particle size of 200 mesh, and mix them at a rotation speed of 30 rpm for 10 min (5 min forward rotation + 5 min reverse rotation). After adding 1000 g of asphalt powder to the mixed powder, transfer it to a ball mill and perform ball milling treatment for 5 h (effective ball milling time) under the conditions of a ball-to-material ratio of 40:1 and a rotation speed of 400 rpm to obtain the first material.

[0086] (2) Transfer the obtained magnesium-lanthanum-nickel-asphalt mixture, that is, the first material, to a tubular furnace and perform calcination in an argon atmosphere, and the calcination conditions are the same as those of the second calcination in Example 5. After the calcined material is ball milled and crushed, a magnesium-lanthanum-nickel-carbon composite hydrogen storage material is obtained.

[0087] That is, the magnesium raw material powder and the lanthanum-nickel alloy raw material powder in this comparative example are not subjected to nanometer treatment and are not subjected to the first calcination treatment either.

[0088] The SEM characterization results of the obtained composite hydrogen storage material are shown in Figure 3 , where the scale bar is 2 μm.

[0089] Testing method

[0090] Particle size (D10, D50, D90): Test according to GB / T 19077 by laser diffraction method for particle size analysis.

[0091] Tap density: Test according to GB / T 5162-2021 for the determination of tap density of powder.

[0092] Specific surface area: Test according to GB / T 19587 by BET method for gas adsorption to determine the specific surface area of solid substances.

[0093] Hydrogen storage performance: In a hydrogen storage tank, determine the hydrogen storage capacity and the hydrogen absorption and desorption cycle performance by the PCT method (set the hydrogen absorption pressure to 3 MPa and the hydrogen desorption pressure to 0.1 MPa during the test). Obtain the hydrogen absorption temperature, hydrogen desorption temperature, hydrogen absorption capacity, hydrogen desorption capacity, maximum hydrogen absorption rate and maximum hydrogen desorption rate.

[0094] Perform the above tests on the composite hydrogen storage materials obtained in each example and comparative example, and the obtained results are shown in Table 1 and Table 2.

[0095] Table 1

[0096]

[0097] Table 2

[0098]

[0099] From the above description, it can be seen that the above embodiments of the present invention achieve the preparation of a composite hydrogen storage material with excellent hydrogen storage performance, which has a lower hydrogen absorption / desorption temperature, a larger hydrogen absorption / desorption capacity, and a faster maximum hydrogen absorption / desorption rate.

[0100] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those described herein.

[0101] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a composite hydrogen storage material, characterized in that, Including: Step S1: Perform plasma nanometrization treatment on magnesium raw material powder and lanthanum-nickel alloy raw material powder respectively to obtain nanosized magnesium powder and nanosized lanthanum-nickel alloy powder; Step S2: Mix the nanosized magnesium powder and the nanosized lanthanum-nickel alloy powder in an inert atmosphere to obtain a mixed powder; add a carbon source to the mixed powder to obtain a first material; the first material is calcined for the first time to obtain a second material; Step S3: The second material is calcined for the second time to obtain the composite hydrogen storage material.

2. The preparation method of the composite hydrogen storage material according to claim 1, characterized in that, In the step S1, The plasma nanometrization treatment is carried out in a plasma nanometrization device, and the process of the plasma nanometrization treatment includes: Turn on the power supply of the plasma nanometrization device, introduce medium gas through the medium gas inlet of the plasma nanometrization device, and the medium gas generates plasma in the plasma torch of the plasma nanometrization device; Introduce sheath gas through the sheath gas inlet of the plasma nanometrization device; introduce cooling gas through the cooling gas inlet of the plasma nanometrization device; Under the action of the feeding carrier gas, the magnesium raw material powder or the lanthanum-nickel alloy raw material powder is conveyed to the plasma generator of the plasma nanometerization device at a feeding speed of 0.4 kg·h -1 ~1.5 kg·h -1 , and is vaporized under the action of the plasma to obtain a material gas; The material gas enters the cooling chamber of the plasma nanometrization device and is cooled by the cooling gas to obtain the nanosized magnesium powder or the nanosized lanthanum-nickel alloy powder.

3. The preparation method of the composite hydrogen storage material according to claim 2, characterized in that, In the step S1, the flow rate of the feeding carrier gas is 0.25 m 3 ·h -1 ~1 m 3 ·h -1 ; and / or, The flow rate of the sheath gas is 3 m 3 ·h -1 ~6 m 3 ·h -1 ; and / or, The flow rate of the medium qi is 2 ± 0.2 m 3 ·h -1 , the voltage of the power supply is 8 ± 0.5 V, and the current is 7 ± 0.5 A.

4. The preparation method of the composite hydrogen storage material according to claim 2 or 3, characterized in that, In the step S1, the flow rate of the cooling gas is 6 m 3 ·h -1 ~8 m 3 ·h -1 , and the pressure of the cooling cavity is 40 kPa to 60 kPa.

5. The preparation method of the composite hydrogen storage material according to any one of claims 1 to 4, characterized in that, In the step S1, The particle size of the magnesium raw material powder is 50 mesh to 200 mesh, preferably 100 mesh to 150 mesh; The particle size of the lanthanum-nickel alloy raw material powder is 100 mesh to 350 mesh, preferably 200 mesh to 300 mesh.

6. The preparation method of the composite hydrogen storage material according to any one of claims 1 to 5, characterized in that, In the step S2, The weight ratio of the nanosized magnesium powder to the nanosized lanthanum-nickel alloy powder is (3 - 19):1; and / or, The ratio of the total weight of the nanosized magnesium powder and the nanosized lanthanum-nickel alloy powder to the weight of the carbon source is (1 - 2):1; Preferably, the carbon source is selected from one or more of asphalt powder, modified asphalt powder and resin powder, and more preferably asphalt powder.

7. The preparation method of the composite hydrogen storage material according to any one of claims 1 to 6, characterized in that, In the step S2, the heating rate of the first calcination is 1°C / min to 5°C / min, the holding temperature is 300°C to 400°C, and the holding time is 2h to 3h.

8. The preparation method of the composite hydrogen storage material according to any one of claims 1 to 7, characterized in that, In the step S3, the heating rate of the second calcination is 2°C / min to 5°C / min, the holding temperature is 500°C to 600°C, and the holding time is 2h to 3h; Preferably, the second calcination is carried out in a protective atmosphere, and more preferably the protective atmosphere is nitrogen and / or argon.

9. A composite hydrogen storage material, characterized in that, The composite hydrogen storage material is prepared by the preparation method of the composite hydrogen storage material according to any one of claims 1 to 7; The specific surface area of the composite hydrogen storage material is 20 m 2 ·g -1 ~70 m 2 ·g -1 ; and / or, The tapped density of the composite hydrogen storage material is 1.4 g·cm -3 ~1.7 g·cm -3 ; and / or, The D10 of the composite hydrogen storage material is 3μm to 6μm, the D50 is 6μm to 10μm, and the D90 is 13μm to 16μm.

10. The composite hydrogen storage material according to claim 9, wherein The hydrogen absorption temperature of the composite hydrogen storage material at 2.5MPa to 3.5MPa is 60°C to 180°C; the hydrogen absorption capacity is 5wt% to 7wt%; the maximum hydrogen absorption rate is 0.70wt% / min to 0.95wt% / min; and / or, The hydrogen desorption temperature of the composite hydrogen storage material is 90°C to 270°C under 0.05 MPa to 0.15 MPa; the hydrogen desorption capacity is 4.5 wt% to 6.5 wt%; the maximum hydrogen desorption rate is 0.2 wt% / min to 0.5 wt% / min.

Images