CN-120717409-B - Nb (Nb) alloy4N5-MgH2Composite hydrogen storage material and preparation method thereof

Abstract

The invention relates to a Nb 4 N 5 -MgH 2 composite hydrogen storage material and a preparation method thereof, wherein the composite hydrogen storage material comprises Nb 4 N 5 and MgH 2 , and the weight percentage of Nb 4 N 5 in the composite hydrogen storage material is 3-9 wt%. The preparation method comprises the following steps of (1) preparing a Nb 4 N 5 catalyst, dissolving NbCl 5 in absolute ethyl alcohol, adding ammonia water to generate precipitate, washing, drying, calcining in an ammonia atmosphere to obtain Nb 4 N 5 catalyst powder, and (2) mixing the Nb 4 N 5 catalyst with MgH 2 , and performing mechanical ball milling to obtain the composite hydrogen storage material. The ball milling process adopts stainless steel balls, argon is used as protective atmosphere, the ball-to-material ratio is (10-40): 1, the ball milling time is 5-12 hours, the rotating speed is 350-500 rpm, and the intermittent ball milling is adopted in the forward and reverse rotation. The composite material prepared by the invention has excellent hydrogen storage dynamic performance. Through the uniform distribution of the Nb 4 N 5 catalyst and the stable phase structure thereof, the hydrogen absorption and desorption performance and the circulation stability of the hydrogen storage material are obviously improved. The invention is suitable for the field of hydrogen energy.

Inventors

• CHEN YUAN
• Yong Meiqi
• Wan Haiyi
• QIU JUNQI
• HU YANG
• GUO ZIYI
• WANG JINGFENG
• PAN FUSHENG

Assignees

• 重庆新型储能材料与装备研究院
• 重庆大学

Dates

Publication Date

20260508

Application Date

20250625

Claims (4)

1. 1. The Nb 4 N 5 -MgH 2 composite hydrogen storage material is characterized by comprising Nb 4 N 5 and MgH 2 , wherein the Nb 4 N 5 in the composite hydrogen storage material is 3 wt-9 wt% in percentage by mass, and the preparation method of the composite hydrogen storage material comprises the following steps: (1) The preparation of the Nb 4 N 5 catalyst comprises the steps of firstly dissolving NbCl 5 in absolute ethyl alcohol, stirring until the solution is clear, adding a proper amount of ammonia water into the solution, stirring and reacting to obtain colloidal precipitate, centrifugally washing the obtained precipitate for a plurality of times by using deionized water and absolute ethyl alcohol, wherein the mass volume ratio of the NbCl 5 to the absolute ethyl alcohol to the ammonia water is (0.5-1) (0.5-5) (10-30), g is mL, stirring and reacting at the speed of 200-800 rpm for 10-60 min, finally, placing the precipitate in a vacuum drying oven to dry to obtain a precursor, then performing temperature programming nitridation, placing a precursor sample in a ceramic crucible, placing the ceramic crucible in a tubular furnace, and calcining after the ammonia gas atmosphere is switched on to obtain Nb 4 N 5 catalyst powder, wherein the temperature programming nitridation parameters are that the temperature programming temperature is raised to 600-900 ℃ at the temperature raising speed of 2-10 ℃ per min, and calcining for 2-8 h; (2) And (3) preparing the Nb 4 N 5 -MgH 2 composite material, namely mixing the Nb 4 N 5 powder and the MgH 2 powder prepared in the step (1), and preparing the Nb 4 N 5 -MgH 2 composite material by adopting mechanical ball milling.
2. 2. The Nb 4 N 5 -MgH 2 composite hydrogen storage material according to claim 1, wherein in the step (1), the concentration of ammonia water is 0.3-0.5 mol/L.
3. 3. The Nb 4 N 5 -MgH 2 composite hydrogen storage material according to claim 1, wherein in the step (1), the centrifugal washing process is that deionized water and absolute ethyl alcohol are centrifugally washed for 3-5 times at a rotating speed of 3000-8000 rpm, and the vacuum drying process is that the vacuum drying is carried out for 8-16 hours at 60-100 ℃.
4. 4. The Nb 4 N 5 -MgH 2 composite hydrogen storage material according to claim 1, wherein in the step (2), a stainless steel ball is adopted in mechanical ball milling, argon is used as ball milling atmosphere, the ball-to-material ratio is (10-40): 1, the ball milling time is 5-12 h, the ball milling rotating speed is 350-500 rpm, and the reverse rotation intermittent ball milling is stopped for 5-30 min after each ball milling time is 5-30 min.

Description

Nb 4N5-MgH2 composite hydrogen storage material and preparation method thereof Technical Field The invention belongs to the technical field of hydrogen energy, and particularly relates to a Nb 4N5-MgH2 composite hydrogen storage material and a preparation method thereof. Background The magnesium-based hydrogen storage material has high hydrogen storage density, the theoretical mass hydrogen storage density and the volume hydrogen storage density are respectively 7.6wt.% and 110g/L, the price is low, the storage quantity is rich, the stable hydrogen absorption and desorption cycle characteristics are realized, and the magnesium-based hydrogen storage material is one of the hydrogen storage materials with the most development prospect at present. However, the development of the method is severely restricted due to high hydrogen release temperature, slow speed and the like caused by high thermodynamic stability and poor dynamic performance. Among all modification strategies, catalyst doping is one of the simplest and effective methods for accelerating the reaction kinetics of the MgH 2 system, and has important theoretical significance for practical application. In previous studies, transition metals and their compounds have been demonstrated to be highly active catalysts for MgH 2. Wherein the presence of the transition metal Nb may facilitate the transport of hydrogen in MgH 2 by a hydrogen pump mechanism. Transition metal nitrides are reported to also have good catalytic effect on the hydrogen absorption/desorption properties of MgH 2. Meanwhile, the transition metal nitride has better stability in an MgH 2/Mg system, can avoid the loss of hydrogen storage capacity caused by the reaction of Mg or MgH 2 and a catalyst, and is beneficial to improving the cycle stability of the material. However, the research on transition metal nitrides is relatively few at present, so that the influence of the transition metal nitrides on the hydrogen storage performance of magnesium hydride is necessary to be researched, and guidance is provided for the subsequent preparation of magnesium hydride catalysts. Disclosure of Invention In order to solve the problems, the invention provides a Nb 4N5-MgH2 composite hydrogen storage material and a preparation method thereof. In order to achieve the above purpose, the present invention provides the following technical solutions: The Nb 4N5-MgH2 composite hydrogen storage material comprises Nb 4N5 and MgH 2, wherein the Nb 4N5 accounts for 3-9 wt% of the composite hydrogen storage material. The preparation method of the Nb 4N5-MgH2 composite hydrogen storage material comprises the following steps: (1) Preparing a Nb 4N5 catalyst, namely firstly dissolving NbCl 5 in absolute ethyl alcohol, stirring until the solution is clear, then adding a proper amount of ammonia water into the solution, stirring and reacting to obtain colloidal precipitate, centrifugally washing the obtained precipitate for a plurality of times by using deionized water and absolute ethyl alcohol, finally, drying the precipitate in a vacuum drying oven to obtain a precursor, then carrying out programmed heating nitridation, placing a precursor sample into a ceramic crucible, placing the ceramic crucible into a tubular furnace, and calcining after the ammonia gas atmosphere is switched on to obtain Nb 4N5 catalyst powder; (2) And (3) preparing the Nb 4N5-MgH2 composite material, namely mixing the Nb 4N5 powder and the MgH 2 powder prepared in the step (1), and preparing the Nb 4N5-MgH2 composite material by adopting mechanical ball milling. In the step (1), the mass volume ratio of NbCl 5 to absolute ethyl alcohol to ammonia water is (0.5 to 5), the mass volume ratio of NbCl to absolute ethyl alcohol to ammonia water is (10 to 30), the mass ratio of NbCl to NbCl is (mL), and the mass ratio of NbCl to NbCl is stirred at a speed of 200 to 800rpm for reaction for 10 to 60 minutes. Further, in the step (1), the concentration of ammonia water is 0.3 to 0.5mol/L. In the step (1), the centrifugal washing process is that deionized water and absolute ethyl alcohol are subjected to centrifugal washing for 3-5 times at the rotating speed of 3000-8000 rpm, and the vacuum drying process is that the vacuum drying is carried out for 8-16 hours at the temperature of 60-100 ℃. In the step (1), the temperature programming nitriding parameters are that the temperature is raised to 600-900 ℃ at a temperature raising rate of 2-10 ℃ per minute, and the calcination is carried out for 2-8 hours. When the temperature reaches 300 ℃, the flow meter is regulated to increase the flow rate of the ammonia gas. In the step (2), stainless steel balls are adopted in mechanical ball milling, argon is used as ball milling atmosphere, the ball-material ratio is (10-40): 1, the ball milling time is 5-12 h, the ball milling rotating speed is 350-500 rpm, and the reverse rotation intermittent ball milling is that the direction is turned once in a pause of