Preparation method of carbon cloth-supported nickel-palladium nanocatalyst and its solid-state hydrogen storage application
By supporting nickel-palladium nanocatalyst on the carbon cloth, the agglomeration and component segregation problems in the preparation of MgH2 catalysts were solved, and the uniform dispersion and efficient hydrogen storage performance of the catalyst were achieved, especially in the hydrogen absorption and discharge reaction of magnesium hydride, which showed excellent catalytic activity and stability.
Patent Information
- Application Number
- CN202311502449.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-13
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2043-11-13
AI Technical Summary
In the prior art, metal nanoparticles are prone to agglomeration, component segregation and complex preparation during the catalyst preparation process of metal hydride MgH2, resulting in insufficient hydrogen storage performance.
Using carbon cloth as a support, the nickel-palladium nanocatalyst supported by carbon cloth is prepared by immersing the nickel-palladium bimetallic salt precursor and combining with strong current to quickly increase and cool down, so as to achieve controllable catalyst components and promote the hydrogen absorption and discharge reaction of MgH2.
The uniform dispersion and efficient catalytic activity of the catalyst were achieved, which significantly improved the hydrogen storage performance of MgH2, especially in terms of hydrogen absorption and discharge kinetics and cycle stability.
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Figure CN117463363B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of new energy solid-state hydrogen storage, and in particular to a preparation method of a carbon cloth-supported nickel-palladium nanocatalyst and its solid-state hydrogen storage application. Background Art
[0002] Hydrogen, a clean and versatile energy carrier, has attracted widespread attention as a potential solution to the global challenges posed by climate change and energy sustainability. Its use in fuel cells, transportation, and industrial processes has the potential to revolutionize energy systems, reducing greenhouse gas emissions and dependence on fossil fuels. However, efficient hydrogen storage remains a key bottleneck to its widespread application.
[0003] Solid-state hydrogen storage, particularly metal hydride hydrogen storage, offers a promising approach due to its high volumetric and gravimetric hydrogen storage capacity and potential for safe applications. Among various metal hydride systems, magnesium hydride (MgH2) has emerged as an ideal candidate for hydrogen storage applications. MgH2 has a theoretical hydrogen storage capacity of up to 7.6 wt%, and the raw material is abundant and relatively low in cost. Furthermore, magnesium is non-toxic, non-flammable, and has low reactivity, making it an attractive hydrogen storage material from a safety perspective. However, the practical application of MgH2 faces several challenges, such as slow kinetics and the high thermodynamics required for hydrogen absorption and desorption. The strong chemical bond between magnesium and hydrogen typically results in a decomposition temperature of pure MgH2 exceeding 350°C, while the slow diffusion rate of H atoms in the hydride also results in a decomposition temperature of MgH2 exceeding 350°C.
[0004] In order to overcome these challenges, many methods have been adopted to improve the performance of magnesium hydride for hydrogen storage. At present, catalytic doping has become a powerful and effective strategy. Especially under the decoration of transition metals (such as Ni, Ti and Co), catalyst doping can mostly form an intermediate phase during the reaction process, thereby reducing the reaction energy barrier of MgH2 and further promoting the absorption and desorption of hydrogen. In fact, the catalytic effect of a single transition metal has limitations. Doping a second transition metal element to form a bimetallic catalyst can make up for this deficiency, achieve a synergistic effect, and further improve the catalytic effect of the hydrogen storage system. In addition, the preparation of the catalyst will affect the apparent morphology and structural properties of the catalyst itself. In this case, selecting a suitable catalyst support and reducing the particle size of the catalyst to the nanoscale are also considered to be other effective methods. At the same time, in order to make the catalyst diffuse and distribute while avoiding agglomeration, different carbon materials are usually selected as the growth support of metal nanocatalysts to promote the preferential nucleation of the catalyst on the host surface. For example, patent CN115301240A discloses a carbon-coated CoNi bimetallic hydrogen storage catalyst, its preparation method and application. The carbon-coated CoNi catalyst is obtained by organic thermal decomposition and the remaining MgH2 is compounded, which greatly improves the hydrogen storage performance of MgH2. However, the catalyst preparation time is too long, the conditions are cumbersome, and the process is complicated.
[0005] In response to the above problems, it is very necessary to develop a simple and fast method to synthesize well-dispersed and uniformly composed nanocatalysts to reduce process costs and improve the hydrogen storage performance of MgH2. Summary of the Invention
[0006] The purpose of the present invention is to provide a method for preparing a carbon cloth-supported nickel-palladium nanocatalyst and its solid-state hydrogen storage application to solve the problems existing in the above-mentioned prior art. The present invention addresses the shortcomings of the catalyst preparation process, such as the easy agglomeration of metal nanoparticles, component segregation, and complex preparation. A method for preparing a carbon cloth-supported nickel-palladium nanocatalyst is provided. Carbon cloth with good conductivity is used as a growth support, and then a palladium-nickel bimetallic salt precursor is impregnated. By connecting a strong current and rapidly heating and cooling, a nickel-palladium nanocatalyst uniformly loaded on the carbon cloth is obtained. The method of the present invention can achieve controllable catalyst components, thereby exerting good catalytic activity in the hydrogen storage reaction of MgH2, which is specifically reflected in the significant improvement in hydrogen absorption and desorption kinetics and cyclic stability.
[0007] To achieve the above object, the present invention provides the following solutions:
[0008] One of the technical solutions of the present invention is to provide a method for preparing a carbon cloth-supported nickel-palladium nanocatalyst, comprising the following steps:
[0009] The carbon cloth is immersed in a nickel-palladium bimetallic salt precursor solution, dried after the immersion, and subjected to an electric treatment under a protective atmosphere. During the electric treatment, the carbon cloth is heat-treated and cooled in sequence to obtain the carbon cloth-loaded nickel-palladium nanocatalyst.
[0010] As a further preferred embodiment of the present invention, the total concentration of nickel-palladium bimetal in the nickel-palladium bimetallic salt precursor solution is 0.05 mol / L, and the molar ratio of nickel to palladium is 0.9:0.1-0.25:0.75.
[0011] The nickel-palladium bimetallic salt precursor solution is prepared by dissolving a palladium salt and a nickel salt in a solvent; the palladium salt is any one of palladium chloride, palladium nitrate, and palladium sulfate; the nickel salt is any one of nickel chloride, nickel nitrate, and nickel sulfate;
[0012] The solvent is preferably an ethanol-based solvent; more preferably a solvent having a volume ratio of ethanol to water of 48:2.
[0013] As a further preferred embodiment of the present invention, the heat treatment is carried out by maintaining the temperature at 1300-1500°C for 30-120 seconds, and the cooling is carried out by cooling the temperature from 1300-1500°C to room temperature within 5 seconds. The room temperature in the present invention is 25°C.
[0014] As a further preferred embodiment of the present invention, the energization treatment adopts direct current treatment, with a current intensity of 375A, a pulse period of 100ms, and a duty cycle of 50%.
[0015] As a further preferred embodiment of the present invention, the carbon cloth is pretreated, wherein the pretreatment step comprises: treating the carbon cloth under hydrogen pressure at 100-300° C. for 0.5-1 hour. Preferably, the hydrogen pressure used is 2-4 MPa.
[0016] The present invention pre-treats the carbon cloth to remove impurities and hydrophilic groups on the surface of the carbon cloth, thereby preventing them from affecting the composition and performance of the catalyst in subsequent reactions; and the hydrogen atmosphere heat treatment can completely remove the groups on the surface of the carbon cloth.
[0017] As a further preferred embodiment of the present invention, the drying temperature is 80° C. and the drying time is 4-6 hours.
[0018] The technical solution of the present invention can realize the rapid preparation of nickel-palladium nanocatalysts. The further preferred technical solution steps are as follows:
[0019] Step 1: Palladium salt and nickel salt are mixed and dissolved in an ethanol-based solution according to a molar ratio to obtain a solution concentration of 0.05 mol / L, followed by magnetic stirring (300-600 rpm) for 4-6 hours to obtain a nickel-palladium bimetallic salt precursor solution;
[0020] Step 2: After washing the carbon cloth with ethanol and letting it dry, perform high-temperature pretreatment at 100-300°C for 0.5-1h under a hydrogen pressure of 2-4 MPa;
[0021] Step 3: Cut the pretreated carbon cloth into small pieces of 2 cm × 5 cm in size and immerse them in a nickel-palladium bimetallic salt precursor solution, and then vacuum dry them at 80° C. for 4 to 6 hours;
[0022] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0023] Step 5: Turn on the current (direct current, current intensity is 375A, pulse period is 100ms, duty cycle is 50%) under protective atmosphere, maintain at 1300-1500°C for 30-120s, and then cool from 1300-1500°C to room temperature within 5s.
[0024] The second technical solution of the present invention is to provide a carbon cloth-supported nickel-palladium nanocatalyst prepared by the above-mentioned preparation method.
[0025] The third technical solution of the present invention is to provide the application of the above-mentioned carbon cloth-supported nickel-palladium nanocatalyst in catalyzing the hydrogen storage performance of magnesium hydride.
[0026] The fourth technical solution of the present invention is to provide a composite hydrogen storage system, comprising the above-mentioned carbon cloth-loaded nickel-palladium nanocatalyst and magnesium hydride.
[0027] As a further preferred embodiment of the present invention, the composite hydrogen storage system is obtained by mixing and ball milling the carbon cloth-supported nickel-palladium nanocatalyst-based magnesium hydride in a mass ratio of 25:75 under a protective atmosphere.
[0028] More preferably, the ball-to-material ratio of the mixed ball milling is 40:1, the ball milling speed is 400 r / min, and the ball milling time is 10 h.
[0029] The present invention discloses the following technical effects:
[0030] This invention uses a carbon support thermal shock method to synthesize uniformly dispersed carbon cloth-supported palladium-nickel nanocatalysts with an average size of 20 to 40 nm. The catalyst preparation method is simple, uses environmentally friendly raw materials, and is easily scalable. It has high application value in catalyzing solid-state hydrogen storage using magnesium hydride. Furthermore, the catalyst composition prepared by this invention is controllable, providing valuable insights into the practical application of catalysts for hydrogen storage.
[0031] The carbon cloth-supported palladium-nickel nanocatalyst prepared by the present invention is mixed with magnesium hydride to form a composite hydrogen storage system, which can effectively improve the hydrogen storage performance of magnesium hydride and has high cycle stability. It has broad application prospects in the field of new energy solid-state hydrogen storage. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0033] Figure 1 Schematic diagram of the preparation of carbon cloth-supported nickel-palladium nanocatalyst by carbon thermal shock in the present invention;
[0034] Figure 2 XRD spectra of carbon cloth-supported palladium-nickel nanocatalysts prepared in Examples 1-4 of the present invention;
[0035] Figure 3 Thermogravimetric (TG) curves of carbon cloth-supported palladium-nickel nanocatalysts prepared in Examples 1-4 of the present invention;
[0036] Figure 4 The XRD refined curves of the carbon cloth supported palladium nickel nanocatalysts prepared in Examples 1-4 of the present invention; wherein (a) is the Ni prepared in Example 4 0.25 Pd 0.75 @CC, (b) is Ni prepared in Example 2 0.75 Pd 0.25 @CC, (c) is Ni prepared in Example 3 0.50 Pd 0.50 @CC, (d) is Ni prepared in Example 1 0.90 Pd 0.10 @CC;
[0037] Figure 5 The SEM images of the carbon cloth-supported palladium-nickel nanocatalysts prepared in Examples 1-4 of the present invention; wherein, (a) is the Ni prepared in Example 4 0.25 Pd 0.75 @CC, (b) is Ni prepared in Example 3 0.50 Pd 0.50 @CC, (c) is Ni prepared in Example 2 0.75 Pd 0.25 @CC, (d) is Ni prepared in Example 1 0.90 Pd 0.10 @CC;
[0038] Figure 6 The temperature-increasing hydrogen release curves of the composite hydrogen storage systems prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention are shown;
[0039] Figure 7The constant temperature hydrogen release curves of the composite hydrogen storage systems prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention are shown;
[0040] Figure 8 The constant temperature hydrogen absorption curves of the composite hydrogen storage systems prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention are shown;
[0041] Figure 9 JMAK curves and Arrhenius curves of the composite hydrogen storage system prepared in Examples 1-4 of the present invention; Figures (a)-(d) are MgH2-Ni 0.90 Pd 0.10 @CC、MgH2-Ni 0.75 Pd 0.25 @CC、MgH2-Ni 0.50 Pd 0.50 @CC、MgH2-Ni 0.25 Pd 0.75 @CC JMAK curve; Figures (e)-(h) are MgH2-Ni 0.90 Pd 0.10 @CC、MgH2-Ni 0.75 Pd 0.25 @CC、MgH2-Ni 0.50 Pd 0.50 @CC、MgH2-Ni 0.25 Pd 0.75 @CC’s Arrhenius curve;
[0042] Figure 10 MgH2-Ni prepared in Example 1 of the present invention 0.90 Pd 0.10 @CC Cycling stability diagram of composite hydrogen storage system;
[0043] Figure 11 This is a cyclic stability diagram of the MgH2 hydrogen storage system prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION
[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.
[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.
[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.
[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.
[0049] Figure 1 The present invention is a flow chart of preparing a carbon cloth-supported nickel-palladium catalyst by carbon thermal shock.
[0050] Example 1
[0051] Preparation of carbon cloth-supported nickel-palladium nanocatalyst (nickel-palladium molar ratio 0.9:0.1) and composite hydrogen storage system:
[0052] Preparation of carbon cloth-supported nickel-palladium nanocatalyst:
[0053] Step 1: Accurately weigh 0.2916 g of nickel chloride and 0.0443 g of palladium chloride and add them to an alcohol-based solution consisting of 48 ml of ethanol and 2 ml of distilled water. The total metal molar concentration in the solution is controlled to be 0.05 mol / L, and stirred with a magnetic stirrer at 500 rpm for 6 h to obtain a nickel-palladium bimetallic salt precursor solution.
[0054] Step 2: The carbon cloth was washed with ethanol and allowed to dry under a hydrogen pressure of 4 MPa, and the temperature was raised to 100°C for 0.5 h.
[0055] Step 3: Cut the pretreated carbon cloth into small pieces of 2cm×5cm in size and immerse them in 3ml of nickel-palladium bimetallic salt precursor solution, controlling the immersion density to 300μL / cm 2 , and then vacuum dried at 80 °C for 6 h;
[0056] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0057] Step 5: Connect 375A current under protective atmosphere, with a pulse period of 100ms and a duty cycle of 50%, maintain at 1300℃ for 30s, and then quickly cool to room temperature within 5s to obtain Ni 0.90 Pd 0.10 @CC Catalyst.
[0058] Preparation of composite hydrogen storage system:
[0059] The Ni in Example 1 0.90 Pd 0.10 @CC catalyst and MgH2 were ball milled in a protective atmosphere at a mass ratio of 25:75, a ball-to-material ratio of 40:1, a ball milling speed of 400 r / min, and a ball milling time of 10 h to obtain MgH2-Ni 0.90 Pd 0.10 @CC composite hydrogen storage system.
[0060] Example 2
[0061] Preparation of carbon cloth-supported nickel-palladium nanocatalyst (nickel-palladium molar ratio 0.75:0.25) and composite hydrogen storage system:
[0062] Preparation of carbon cloth-supported nickel-palladium nanocatalyst:
[0063] Step 1: Accurately weigh 0.2430 g of nickel chloride and 0.1108 g of palladium chloride and add them to an alcohol-based solution consisting of 48 ml of ethanol and 2 ml of distilled water. The total metal molar concentration in the solution is controlled to be 0.05 mol / L, and stirred with a magnetic stirrer at 500 rpm for 6 h to obtain a nickel-palladium bimetallic salt precursor solution.
[0064] Step 2: The carbon cloth was washed with ethanol and allowed to dry under a hydrogen pressure of 4 MPa, and the temperature was raised to 100°C for 0.5 h.
[0065] Step 3: Cut the pretreated carbon cloth into small pieces of 2cm×5cm in size and immerse them in 3ml of nickel-palladium bimetallic salt precursor solution, controlling the immersion density to 300μL / cm 2 , and then vacuum dried at 80 °C for 6 h;
[0066] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0067] Step 5: Connect 375A current under protective atmosphere, with a pulse period of 100ms and a duty cycle of 50%, maintain at 1300℃ for 30s, and then quickly cool to room temperature within 5s to obtain Ni 0.75 Pd 0.25 @CC Catalyst.
[0068] Preparation of composite hydrogen storage system:
[0069] The Ni in Example 2 0.75 Pd 0.25 @CC catalyst and MgH2 were ball milled in a protective atmosphere at a mass ratio of 25:75, a ball-to-material ratio of 40:1, a ball milling speed of 400 r / min, and a ball milling time of 10 h to obtain MgH2-Ni 0.75 Pd 0.25 @CC composite hydrogen storage system.
[0070] Example 3
[0071] Preparation of carbon cloth-supported nickel-palladium nanocatalyst (nickel-palladium molar ratio 0.50:0.50) and composite hydrogen storage system:
[0072] Preparation of carbon cloth-supported nickel-palladium nanocatalyst:
[0073] Step 1: Accurately weigh 0.1620 g of nickel chloride and 0.2217 g of palladium chloride and add them to an alcohol-based solution consisting of 48 ml of ethanol and 2 ml of distilled water. The total metal molar concentration in the solution is controlled to be 0.05 mol / L, and stirred with a magnetic stirrer at 500 rpm for 6 h to obtain a nickel-palladium bimetallic salt precursor solution.
[0074] Step 2: The carbon cloth was washed with ethanol and allowed to dry under a hydrogen pressure of 4 MPa, and the temperature was raised to 100°C for 0.5 h.
[0075] Step 3: Cut the pretreated carbon cloth into small pieces of 2cm×5cm in size and immerse them in 3ml of nickel-palladium bimetallic salt precursor solution, controlling the immersion density to 300μL / cm 2 , and then vacuum dried at 80 °C for 6 h;
[0076] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0077] Step 5: Connect 375A current under protective atmosphere, with a pulse period of 100ms and a duty cycle of 50%, maintain at 1300℃ for 30s, and then quickly cool to room temperature within 5s to obtain Ni0.50 Pd 0.50 @CC Catalyst.
[0078] Preparation of composite hydrogen storage system:
[0079] The Ni in Example 3 0.50 Pd 0.50 @CC catalyst and MgH2 were ball milled in a protective atmosphere at a mass ratio of 25:75, a ball-to-material ratio of 40:1, a ball milling speed of 400 r / min, and a ball milling time of 10 h to obtain MgH2-Ni 0.50 Pd 0.50 @CC composite hydrogen storage system.
[0080] Example 4
[0081] Preparation of carbon cloth-supported nickel-palladium nanocatalyst (nickel-palladium molar ratio 0.25:0.75) and composite hydrogen storage system:
[0082] Preparation of carbon cloth-supported nickel-palladium nanocatalyst:
[0083] Step 1: Accurately weigh 0.0810 g of nickel chloride and 0.3325 g of palladium chloride and add them to an alcohol-based solution consisting of 48 ml of ethanol and 2 ml of distilled water. The total metal molar concentration in the solution is controlled to be 0.05 mol / L, and stirred with a magnetic stirrer at 500 rpm for 6 h to obtain a nickel-palladium bimetallic salt precursor solution.
[0084] Step 2: The carbon cloth was washed with ethanol and allowed to dry under a hydrogen pressure of 4 MPa, and the temperature was raised to 100°C for 0.5 h.
[0085] Step 3: Cut the pretreated carbon cloth into small pieces of 2cm×5cm in size and immerse them in 3ml of nickel-palladium bimetallic salt precursor solution, controlling the immersion density to 300μL / cm 2 , and then vacuum dried at 80 °C for 6 h;
[0086] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0087] Step 5: Connect 375A current under protective atmosphere, with a pulse period of 100ms and a duty cycle of 50%, maintain at 1300℃ for 30s, and then quickly cool to room temperature within 5s to obtain Ni 0.25 Pd 0.75 @CC Catalyst.
[0088] Preparation of composite hydrogen storage system:
[0089] The Ni in Example 4 0.25 Pd 0.75@CC catalyst and MgH2 were ball milled in a protective atmosphere at a mass ratio of 25:75, a ball-to-material ratio of 40:1, a ball milling speed of 400 r / min, and a ball milling time of 10 h to obtain MgH2-Ni 0.25 Pd 0.75 @CC composite hydrogen storage system.
[0090] The carbon cloth-supported nickel-palladium nanocatalysts prepared in Examples 1-4 were structurally characterized:
[0091] Figure 2 Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x X-ray diffraction (XRD) patterns of @CC (x=0.25, 0.5, 0.75, 0.90) catalysts show that the present invention successfully synthesized carbon cloth-supported nickel-palladium nanocatalysts. At the same time, it can be observed from the figure that with the increase of Pd content, the intensity of the main diffraction peak regularly shifts to the left, and no phase separation phenomenon is found, indicating that Pd is successfully doped into the Ni matrix, resulting in lattice expansion, proving that the nickel-palladium catalyst exists in the form of a solid solution alloy.
[0092] Figure 3 Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x Thermogravimetric curves (TG) of @CC (x = 0.25, 0.5, 0.75, 0.90) catalysts show that when the temperature reaches above 450 ° C, the thermal decomposition of carbon cloth causes the catalyst to lose weight rapidly, and the final remaining weight percentage stabilizes in the range of 17.1-23.8 wt%, which is Ni x Pd 1-x (x=0.25, 0.5, 0.75, 0.90) Catalyst loading on carbon cloth.
[0093] Figure 4 Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x The XRD refinement results of @CC (x=0.25, 0.5, 0.75, 0.90) catalysts show that Ni x Pd 1-x The phase content of (x=0.25, 0.5, 0.75, 0.90) is around 20 wt%, which is consistent with the TG results.
[0094] Figure 5 Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-xScanning electron microscopy (SEM) images of @CC (x = 0.25, 0.5, 0.75, 0.90) catalysts show that the Ni x Pd 1-x (x=0.25, 0.5, 0.75, 0.90) The catalysts grew uniformly and dispersed well on the carbon cloth without agglomeration. 0.9 Pd 0.1 The best growth effect of @CC is at an average size of 28.6nm.
[0095] Comparative Example 1 Preparation of a Single Nickel Catalyst and a Composite Hydrogen Storage System
[0096] Preparation of single nickel catalyst:
[0097] Step 1: Accurately weigh 0.3240 g of nickel chloride and add it to an alcohol-based solution consisting of 48 ml of ethanol and 2 ml of distilled water. The total metal molar concentration in the solution is controlled to be 0.05 mol / L. The mixture is stirred at 500 rpm for 6 h using a magnetic stirrer to obtain a precursor metal salt solution.
[0098] Step 2: The carbon cloth was washed with ethanol and allowed to dry under a hydrogen pressure of 4 MPa, and the temperature was raised to 100°C for 0.5 h.
[0099] Step 3: Cut the pretreated carbon cloth into small pieces of 2cm×5cm in size and immerse them in 3ml of precursor solution, controlling the immersion density to 300μL / cm 2 , and then vacuum drying was performed at 80°C for 6h;
[0100] Step 4: The treated carbon cloth is fixed with graphite sheets and connected through graphite electrodes at both ends;
[0101] Step 5: Under a protective atmosphere, a current of 375 A is applied, with a pulse period of 100 ms and a duty cycle of 50%, and the temperature is maintained at 1300° C. for 30 s. The temperature is then rapidly cooled to room temperature within 5 s to obtain a Ni@CC catalyst.
[0102] Preparation of composite hydrogen storage system:
[0103] The Ni@CC catalyst and MgH2 in Comparative Example 1 were ball-milled in a mass ratio of 25:75 under a protective atmosphere, with a ball-to-material ratio of 40:1, a ball-milling speed of 400 r / min, and a ball-milling time of 10 h to obtain a MgH2-Ni@CC composite hydrogen storage system.
[0104] Comparative Example 2 Preparation of Carbon Cloth Doped MgH2 Composite Hydrogen Storage System
[0105] Carbon cloth and MgH2 were ball-milled in a protective atmosphere at a mass ratio of 25:75, a ball-to-material ratio of 40:1, a ball-milling speed of 400 r / min, and a ball-milling time of 10 h to obtain a MgH2-CC composite hydrogen storage system.
[0106] Comparative Example 3 Preparation of MgH2 Hydrogen Storage System
[0107] MgH2 was ball-milled under a protective atmosphere with a ball-to-material ratio of 40:1, a ball-milling speed of 400 r / min, and a ball-milling time of 10 h to obtain As milled MgH2.
[0108] Figure 6 MgH2-Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x @CC (x = 0.25, 0.5, 0.75, 0.90) and the temperature-increasing hydrogen desorption curves of the composite hydrogen storage systems of Comparative Examples 1 to 3. The results show that the MgH2 composite hydrogen storage system doped with nickel-palladium catalyst exhibits a lower initial hydrogen desorption temperature, among which MgH2-Ni 0.9 Pd 0.1 The @CC composite material has the best effect, with an initial hydrogen desorption temperature of 486K, which is much lower than the 577K of MgH2.
[0109] Figure 7 MgH2-Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x @CC (x = 0.25, 0.5, 0.75, 0.90) and the constant temperature hydrogen desorption curves of the composite hydrogen storage systems of Comparative Examples 1 to 3. The results show that the MgH2 composite hydrogen storage system doped with nickel palladium catalyst exhibits a more excellent hydrogen desorption efficiency, among which MgH2-Ni 0.9 Pd 0.1 The @CC composite material has the best effect, and it only takes 7 minutes to release 5.69wt% of hydrogen at 573K, indicating that the doping of nickel target catalyst reduces the hydrogen decomposition barrier of MgH2, accelerates the dehydrogenation rate, and improves the dehydrogenation efficiency.
[0110] Figure 8 MgH2-Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x @CC (x = 0.25, 0.5, 0.75, 0.90) and the constant temperature hydrogen absorption curves of the composite hydrogen storage systems of comparative examples 1 to 3. The results show that the MgH2 composite hydrogen storage system doped with nickel palladium catalyst greatly improves the hydrogen absorption capacity at low temperatures, among which MgH2-Ni 0.9 Pd 0.1The @CC composite showed the best effect, rapidly absorbing 3.10 wt% hydrogen even at 373 K.
[0111] Figure 9 MgH2-Ni prepared rapidly by carbon thermal shock in Examples 1 to 4 x Pd 1-x JMAK curves and Arrhenius curves of @CC (x=0.25、0.5、0.75、0.90). The results show that the MgH2 composite hydrogen storage system doped with nickel-palladium catalysts all exhibits a low activation energy for hydrogen release, among which MgH2-Ni 0.9 Pd 0.1 @CC composite material was reduced to 76.9kJ / mol.
[0112] Figures 10-11 They are MgH2-Ni prepared by carbon thermal shock in Example 1 0.9 Pd 0.1 @CC and the cycling stability diagram of MgH2 in comparative example 3 show that MgH2-Ni 0.9 Pd 0.1 The @CC composite material has the best cyclic stability. After thirty cycles at 300°C, the hydrogen absorption and desorption amounts are 5.59wt% and 5.38wt%, respectively, and the hydrogen absorption and desorption capacity retention rates are 97.7% and 95.6%, respectively. In comparison, the hydrogen absorption and desorption amounts of MgH2 are only 4.06% and 4.03%, and the hydrogen absorption and desorption capacity retention rates are only 65.5% and 62.5%, respectively. This shows that the composite material doped with nickel target catalyst has a significant improvement in the cyclic performance.
[0113] The composite hydrogen storage system of the present invention exhibits excellent hydrogen storage performance, wherein MgH2-Ni 0.9 Pd 0.1 The @CC system has the best performance. Its initial dehydrogenation temperature is reduced to 486K compared to 577K of MgH2, and it takes only 7 minutes to reach a dehydrogenation rate of 5.69wt% at a temperature of 573K. At the same time, the apparent activation energy of dehydrogenation is 76.9kJ / mol, which significantly reduces the kinetic barrier of the dehydrogenation reaction of MgH2 and improves its dehydrogenation performance. 0.9 Pd 0.1 The @CC composite hydrogen storage system has a hydrogen absorption capacity and hydrogen desorption capacity retention rate of 97.7% and 95.6% after thirty cycles, respectively, which is a significant improvement compared to 65.5% and 62.5% of MgH2.
[0114] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.
Claims
1. A method for preparing a carbon cloth-supported nickel-palladium nanocatalyst, characterized in that: The following steps are involved: The carbon cloth is immersed in a nickel-palladium bimetallic salt precursor solution, dried after the impregnation, and the obtained carbon cloth is subjected to an electric treatment under a protective atmosphere, and is heat-treated and cooled in sequence during the electric treatment to obtain the carbon cloth-supported nickel-palladium nanocatalyst: The impregnation density is 300-500 μL / cm 2 The heat treatment method is: maintaining at 1300~1500 ℃ for 30~120s; the cooling method is: cooling from 1300~1500 ℃ to room temperature within 5s; The energization process adopts direct current process, the current intensity is 375A, the pulse period is 100ms, and the duty cycle is 50%.
2. The preparation method according to claim 1, characterized in that The total concentration of nickel-palladium bimetal in the nickel-palladium bimetallic salt precursor solution is 0.05 mol / L, and the molar ratio of nickel to palladium is 0.9:0.1-0.25:0.
75.
3. The preparation method according to claim 1, characterized in that The carbon cloth is pretreated; the pretreatment step includes: treating the carbon cloth under hydrogen pressure at 100-300° C. for 0.5-1 hour.
4. The preparation method according to claim 1, characterized in that The drying temperature is 80°C.
5. The carbon cloth-supported nickel-palladium nanocatalyst prepared by the preparation method according to any one of claims 1 to 4.
6. Use of the carbon cloth-supported nickel palladium nanocatalyst as claimed in claim 5 in catalyzing the hydrogen storage performance of magnesium hydride.
7. A composite hydrogen storage system, characterized in that: The invention comprises the carbon cloth-supported nickel palladium nanocatalyst according to claim 5 and magnesium hydride.
8. The composite hydrogen storage system according to claim 7, characterized in that: The composite hydrogen storage system is obtained by mixing and ball-milling the carbon cloth-supported nickel-palladium nanocatalyst and magnesium hydride in a mass ratio of 25:75 under a protective atmosphere.