Preparation method of polyaniline and Grignard reagent in-situ modified rare earth magnesium-based hydrogen storage material
阅读说明：本技术 聚苯胺和格式试剂原位修饰稀土镁基储氢材料的制备方法 (Preparation method of polyaniline and Grignard reagent in-situ modified rare earth magnesium-based hydrogen storage material ) 是由 刘宾虹 高子钧 李洲鹏 于 2020-12-09 设计创作，主要内容包括：本发明涉及金属材料储氢技术,旨在提供一种聚苯胺和格式试剂原位修饰稀土镁基储氢材料的制备方法。包括：以无水氯化镁、无水氯化钾、无水氯化钡、无水氟化钙,球磨混合得到熔炼覆盖熔剂；然后与块状金属镁和稀土金属进行2次翻身重熔,冷却后得到块状的稀土镁合金,挫取碎屑；将引发剂溶液滴加至苯胺溶液中,经聚合得到小分子聚苯胺；溶解于水中后加热蒸发,得到聚苯胺预聚溶液；加入稀土镁合金碎屑,搅拌反应后过滤、干燥,得到产品。本发明有利于降低放氢反应活化能,降低放氢温度,提高放氢速度。降低镁吸氢反应活化能,降低稀土镁合金吸氢温度,提高吸氢速度。可用于制造商业化应用的便携和移动式电源,应用于电动汽车、电子产品等。(The invention relates to a metal material hydrogen storage technology, and aims to provide a preparation method of a polyaniline and Grignard reagent in-situ modified rare earth magnesium-based hydrogen storage material. The method comprises the following steps: carrying out ball milling and mixing on anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride to obtain a smelting covering flux; then remelting the magnesium alloy, massive magnesium and rare earth metal in a turnover manner for 2 times, cooling to obtain massive rare earth magnesium alloy, and fetching scraps; dropwise adding an initiator solution into an aniline solution, and polymerizing to obtain micromolecular polyaniline; dissolving the polyaniline in water, and heating and evaporating to obtain a polyaniline prepolymer solution; adding rare earth magnesium alloy fragments, stirring for reaction, filtering and drying to obtain the product. The invention is beneficial to reducing the activation energy of the hydrogen discharge reaction, reducing the hydrogen discharge temperature and improving the hydrogen discharge speed. The activation energy of the magnesium hydrogen absorption reaction is reduced, the hydrogen absorption temperature of the rare earth magnesium alloy is reduced, and the hydrogen absorption speed is increased. Can be used for manufacturing portable and mobile power supplies for commercial application, electric automobiles, electronic products and the like.)
1. A preparation method of polyaniline and Grignard reagent in-situ modification rare earth magnesium-based hydrogen storage material is characterized by comprising the following steps:
(1) taking powder-shaped anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride according to the mass ratio of 4: 1, and carrying out ball milling and mixing for 1-2 hours to obtain a smelting covering flux;
(2) spreading a smelting covering flux at the bottom of the crucible, putting massive magnesium metal and rare earth metal on the smelting covering flux according to the molar ratio of 8.5-12: 1 to form a material bed, and then covering a layer of smelting covering flux on the surface of the material bed; covering a crucible cover, and placing the crucible in a well type furnace; heating to 700-850 ℃, preserving heat for 1-2 hours, and cooling to room temperature; spreading a smelting covering flux at the bottom of the crucible, placing the turned sample, and covering a layer of smelting covering flux on the surface of the sample; covering a crucible cover, and performing turnover smelting according to the same heating, heat preservation and cooling processes; performing turnover remelting for 2 times in total, and cooling to obtain blocky rare earth magnesium alloy;
(3) polishing the massive rare earth magnesium alloy to remove surface oxide skin, and filing the rare earth magnesium alloy scraps by using a file for later use;
(4) dissolving 5g of aniline in 100mL of deionized water at 90 ℃, and dispersing for 5 minutes by ultrasonic vibration to obtain an aniline solution; adding 2g of sodium persulfate into 50mL of 1M hydrochloric acid, and dissolving to obtain an initiator solution;
(5) dropwise adding an initiator solution into an aniline solution, heating to 90 ℃, and polymerizing aniline after ultrasonic vibration dispersion for 30 minutes to obtain a prepolymer; adding NaOH solution to adjust the pH value to be neutral so as to terminate polymerization, thereby obtaining micromolecular polyaniline; dissolving the polyaniline in water, and heating and evaporating to obtain a polyaniline pre-polymerization solution with the mass percent of 5-10%;
(6) taking 5-10 g of rare earth magnesium alloy scraps, and adding the rare earth magnesium alloy scraps into 100mL of polyaniline prepolymerization solution; stirring for reaction for 30min, filtering, and drying at 80 deg.C to obtain polyaniline-modified rare earth magnesium-based hydrogen storage material.
2. The method according to claim 1, wherein the rare earth metal is metal La or metal Ce, or a mischmetal having La or Ce as a main component.
3. The method of claim 1, wherein in step (2), the thickness of each layer of smelting cover flux is in excess of 2 mm.
4. The method according to claim 1, wherein in the step (2), the temperature increase rate during the warming is controlled to 10 ℃/min.
5. The method according to claim 1, wherein in the step (2), the temperature increase rate during the warming is controlled to be 1 ℃/min.
Technical Field
The invention relates to a metal material hydrogen storage technology, in particular to a preparation method of a polyaniline and Grignard reagent in-situ modified rare earth magnesium-based hydrogen storage material.
Background
Hydrogen energy is clean, environment-friendly and renewable, and is considered as the most ideal secondary energy in the 21 st century, and the technology of fuel cells (PEMFCs) with proton exchange membranes as electrolytes is mature day by day. Hydrogen gas, which is a fuel for fuel cells, is stored in two major categories, physical and chemical. The physical method mainly comprises the following steps: liquid hydrogen storage, high pressure hydrogen storage, glass microsphere storage, underground cavern storage, activated carbon adsorption storage, carbon nanotube storage (including partial chemisorption storage as well). The chemical method mainly comprises the following steps: metal hydride storage, organic liquid hydride storage, inorganic storage, and the like.
The metal hydrogen storage alloy has strong capability of capturing hydrogen, hydrogen molecules can be decomposed into single atoms on the surface of the alloy under certain temperature and pressure conditions, the single atoms and the alloy are subjected to chemical reaction to generate metal hydride, and the metal hydride is externally expressed as a large amount of hydrogen absorbed and heat is released at the same time. When these metal hydrides are heated, they undergo decomposition reaction, and hydrogen atoms can be combined into hydrogen molecules to be released, and the hydrogen molecules are accompanied by obvious endothermic effect. The hydrogen storage alloy is adopted to store hydrogen, so that the energy consumption is low, the working pressure is low, the use is convenient, and a huge steel container can be omitted, so that the storage and the transportation are convenient and safe. The existing hydrogen storage alloy mainly comprises titanium-series, zirconium-series, magnesium-series and rare earth-series hydrogen storage alloys, wherein metal magnesium has high hydrogen storage density of 7.6 wt%, can realize reversible hydrogen absorption and desorption, has high storage and transportation efficiency, abundant resources and low price, and is an ideal hydrogen storage material.
Since magnesium metal is relatively active, the surface of magnesium metal is usually covered by a dense oxide film. Although the compact oxide film prevents the magnesium metal from being further oxidized, the surface protection effect is achieved, the hydrogen permeability is also hindered, the activation is difficult, the hydrogen absorption and desorption speed of the magnesium metal is low, the actual hydrogen absorption and desorption temperature is high, and the practical process of the magnesium metal is seriously hindered. The method for improving the hydrogen absorption and desorption performance of magnesium mainly comprises the following steps: one is alloying, and the hydrogen absorption and desorption reaction is catalyzed by adding an alloy element, but the alloy density is increased, and the hydrogen storage capacity is reduced. And secondly, surface treatment, namely forming a surface protective layer which is easy to permeate hydrogen and blocks oxygen by eliminating a compact magnesium oxide film, thereby improving the hydrogen absorption and desorption speed performance under the condition of not changing the hydrogen storage density of magnesium.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provides a preparation method of a polyaniline and Grignard reagent in-situ modified rare earth magnesium-based hydrogen storage material.
In order to solve the technical problem, the solution of the invention is as follows:
the method for in-situ modification of the rare earth magnesium-based hydrogen storage material by polyaniline and Grignard reagent comprises the following steps:
(1) taking powder-shaped anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride according to the mass ratio of 4: 1, and carrying out ball milling and mixing for 1-2 hours to obtain a smelting covering flux;
(2) spreading a smelting covering flux at the bottom of the crucible, putting massive magnesium metal and rare earth metal on the smelting covering flux according to the molar ratio of 8.5-12: 1 to form a material bed, and then covering a layer of smelting covering flux on the surface of the material bed; covering a crucible cover, and placing the crucible in a well type furnace; heating to 700-850 ℃, preserving heat for 1-2 hours, and cooling to room temperature; spreading a smelting covering flux at the bottom of the crucible, placing the turned sample, and covering a layer of smelting covering flux on the surface of the sample; covering a crucible cover, and performing turnover smelting according to the same heating, heat preservation and cooling processes; performing turnover remelting for 2 times in total, and cooling to obtain blocky rare earth magnesium alloy;
(3) polishing the massive rare earth magnesium alloy to remove surface oxide skin, and filing the rare earth magnesium alloy scraps by using a file for later use;
(4) dissolving 5g of aniline in 100mL of deionized water at 90 ℃, and dispersing for 5 minutes by ultrasonic vibration to obtain an aniline solution; adding 2g of sodium persulfate into 50mL of 1M hydrochloric acid, and dissolving to obtain an initiator solution;
(5) dropwise adding an initiator solution into an aniline solution, heating to 90 ℃, and polymerizing aniline after ultrasonic vibration dispersion for 30 minutes to obtain a prepolymer; adding NaOH solution to adjust the pH value to be neutral so as to terminate polymerization, thereby obtaining micromolecular polyaniline; dissolving the polyaniline in water, and heating and evaporating to obtain a polyaniline pre-polymerization solution with the mass percent of 5-10%;
(6) taking 5-10 g of rare earth magnesium alloy scraps, and adding the rare earth magnesium alloy scraps into 100mL of polyaniline prepolymerization solution; stirring for reaction for 30min, filtering, and drying at 80 deg.C to obtain polyaniline-modified rare earth magnesium-based hydrogen storage material.
In the invention, the rare earth metal is metal La or metal Ce, or mixed rare earth metal (such as lanthanum-rich mixed rare earth Ml and cerium-rich mixed rare earth Mm) taking La or Ce as a main component.
In the invention, in the step (2), the thickness of each layer of smelting covering flux is more than 2 mm.
In the present invention, in the step (2), the temperature increase rate during heating is controlled to 10 ℃/min.
In the present invention, in the step (2), the temperature increase rate during heating is controlled to 1 ℃/min.
Description of the inventive principles:
polyaniline is a high molecular compound, has special electrical and optical properties, and can have conductivity and electrochemical properties after being doped. Polyaniline has been widely studied and applied because of its easily available raw materials, simple synthesis process, good chemical and environmental stability, and the like. The material can be applied to urease sensors of biological or chemical sensors, electron field emission sources, selective membrane materials, antistatic and electromagnetic shielding materials, conductive fibers, anticorrosive materials and the like.
Aniline is a colorless oily liquid. Melting point-6.3 deg.C, boiling point 184 deg.C, slightly soluble in water, and easily soluble in organic solvents such as ethanol and diethyl ether. N in aniline is sp3Hybridized but very nearly sp2Hybridization, the orbit occupied by the lone pair of electrons can be conjugated with benzene ring, and the electron cloud can be dispersed in benzeneOn the ring, the electron cloud density around the nitrogen is reduced. Respectively dissolving a proper amount of aniline and an initiator (such as persulfate) in dilute hydrochloric acid, then quickly mixing the aniline and the initiator and continuously stirring the mixture to gradually turn the solution into dark green to form the HCl-doped polyaniline.
The conductivity of polyaniline comes from the pi-electron conjugated structure in the molecular chain: along with the enlargement of a pi electron system on a molecular chain, a valence band and a conduction band are respectively formed in a bonding state and a pi-reverse bonding state, and the non-localized pi electron conjugated structure can form a P-type conduction state and an N-type conduction state after being doped. Different from the doping mechanism of other conducting polymers which generate cation vacancy under the action of an oxidant, the electron number is not changed in the doping process of polyaniline, but H is generated by the decomposition of doped protonic acid+And for anions (e.g. Cl)-Sulfate, phosphate, etc.) into the main chain, and combines with the N atoms in amine and imine groups to form a dipole and a dipole, delocalized to the conjugated pi-bond of the whole molecular chain, so that the polyaniline exhibits higher conductivity. The unique doping mechanism makes the doping and de-doping of polyaniline completely reversible, and the doping degree is influenced by factors such as pH value, potential and the like.
The Grignard reagent is a reagent with a general formula of R-Mg-X, wherein R is aliphatic hydrocarbon group or aromatic hydrocarbon group, and X is halogen. The Grignard reagent is a covalent compound (alkyl magnesium halide) generated by the action of halogenated hydrocarbon and metal magnesium in anhydrous ether or tetrahydrofuran, a magnesium atom is directly connected with a carbon to form a polar covalent bond, and the carbon is an electronegative end, so the Grignard reagent is a very strong Lewis base and can abstract protons from other Lewis acids to generate corresponding hydrocarbyl.
On the basis of smelting to form the rare earth magnesium-based alloy, polyaniline based on rare earth-nitrogen coordination bonds is formed on the surface of the alloy through surface modification to serve as a hydrogen desorption catalytic site, and a strong dipole pair formed by a surface format reagent of phenylmagnesium fluoride and the polyaniline is formed to promote magnesium to absorb hydrogen, so that the high-capacity hydrogen storage material for catalyzing metal magnesium to absorb and desorb hydrogen is realized.
Magnesium hydride (MgH)2) The hydrogen in (2) is present in the form of negative ions. The main chain of polyaniline is positively charged (protonated) and forms phenyl anions on adjacent phenylmagnesium fluorideThe strong dipole pair polarizes hydrogen molecules, which is beneficial to the formation of hydride, therefore, the dipole pair of the Grignard reagent phenylmagnesium fluoride and polyaniline promotes the hydrogenation of magnesium to form MgH2. And fluoride ion (F) contained in phenylmagnesium fluoride-) With MgH2Hydrogen anion (H) of (1)-) In contrast, in phenylmagnesium fluoride and MgH2Interface F-And H-The positions can be interchanged, but F-And H-Is completely different, and the hydride ion loses electrons more easily than the fluoride ion. In the process of hydrogen evolution, MgH2Hydrogen anion of (1) H-The loss of electron exchange and the deprotonation of polyaniline form hydrogen atoms, and the hydrogen atoms are coupled to form hydrogen molecules, so that the presence of polyaniline catalyzes MgH2To discharge hydrogen.
Compared with the prior art, the invention has the beneficial effects that:
1. the rare earth magnesium-based alloy is formed by smelting, so that a compact oxide film is not favorably formed; polyaniline based on rare earth-nitrogen coordination bonds is formed on the surface of the alloy through surface modification and serves as a hydrogen discharge catalytic site, so that the reduction of the activation energy of the hydrogen discharge reaction is facilitated, the hydrogen discharge temperature is reduced, and the hydrogen discharge speed is increased.
2. The strong dipole pair formed by the phenyl magnesium fluoride serving as a Grignard reagent and the polyaniline is formed on the surface of the rare earth magnesium-based alloy to promote the polarization of hydrogen molecules, so that the hydrogen absorption reaction activation energy of magnesium is favorably reduced, the hydrogen absorption temperature of the rare earth magnesium alloy is reduced, and the hydrogen absorption speed is improved.
3. The invention uses polyaniline and Grignard reagent to modify the high hydrogen storage capacity of rare earth magnesium alloy, and the polyaniline and Grignard reagent are used as large-capacity hydrogen storage media to provide pure hydrogen for fuel cells, so that the polyaniline and Grignard reagent can be manufactured into portable and mobile power supplies for large-scale commercial application, and can be applied to electric automobiles, electronic products, military equipment and the like.
Drawings
FIG. 1 shows the surface in situ modified La of the present invention obtained in example 82Mg17And the hydrogen absorption curve of the magnesium metal.
Fig. 2 is a comparison of the hydrogen release curves of the surface in-situ modified cerium-magnesium alloy hydride and the metal magnesium hydride obtained in example 9.
The reference numbers in the figures are: 1-1 hydrogen absorption heating temperature curve, 1-2 surface in situ modification La of the invention2Mg17The hydrogen absorption curve of the invention, 1-3 the hydrogen absorption curve of metal magnesium powder from vendors, 2-1 the hydrogen release heating temperature curve, 2-2 the hydrogen release curve of metal magnesium hydride, 2-3 the hydrogen release curve of the surface in-situ modified cerium magnesium alloy hydride of the invention.
Detailed Description
The present invention will be described in detail below.
Example 1: preparation of magnesium alloy smelting covering flux
Anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride powder are mixed for 1 hour in a ball milling mode according to the mass ratio of 4: 1 to obtain the magnesium alloy smelting covering flux.
Example 2: la2Mg17Preparation of the alloy
Anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride powder are mixed for 1.5 hours in a ball milling mode according to the mass ratio of 4: 1 to obtain the magnesium alloy smelting covering flux.
Placing small pieces of metal magnesium and metal lanthanum in a crucible with the bottom spread with the smelting covering flux (more than 2cm, the same below) according to the mol ratio of 8.5: 1 to form a material bed, laying a layer of smelting covering flux on the material bed, covering the crucible cover, and placing the crucible cover in a well type furnace; heating to 700 deg.C at a speed of 10 deg.C/min, and maintaining for 2 hr; cooling to room temperature, turning over the sample, putting the sample in a crucible with the melting covering flux spread at the bottom, spreading a layer of melting covering flux on the crucible, covering the crucible cover, and turning over and melting; remelting the mixture after 2 times of turnover, and cooling to obtain La2Mg17Rare earth magnesium alloy.
Example 3: CeMg12Preparation of the alloy
Anhydrous magnesium chloride, anhydrous potassium chloride, anhydrous barium chloride and anhydrous calcium fluoride powder are mixed for 2 hours in a ball milling mode according to the mass ratio of 4: 1 to obtain the magnesium alloy smelting covering flux.
Placing small pieces of metal magnesium and metal cerium at the bottom according to the mol ratio of 12: 1, and spreading the above materialsSmelting the crucible covered with the flux to form a material bed, laying a layer of smelting covering flux on the material bed, covering a crucible cover, and placing the crucible cover in a well type furnace; heating to 775 deg.C at 10 deg.C/min, and maintaining for 1.5 hr; cooling to room temperature, turning over the sample, putting the sample in a crucible with the melting covering flux spread at the bottom, spreading a layer of melting covering flux on the crucible, covering the crucible cover, and turning over and melting; remelting the mixture after 2 times of turnover, and cooling the mixture to obtain CeMg12Rare earth magnesium alloy.
Example 4: preparation of mixed rare earth magnesium alloy
Placing small pieces of metal magnesium and lanthanum-rich mixed rare earth (Ml) into a crucible, the bottom of which is paved with the smelting covering flux obtained in the example 1 according to the mol ratio of 10: 1 to form a material bed, paving a layer of smelting covering flux on the material bed, covering a crucible cover, and placing the crucible cover into a well type furnace; heating to 800 deg.C at a speed of 10 deg.C/min, and maintaining for 1 hr; cooling to room temperature, turning over the sample, putting the sample in a crucible with the melting covering flux spread at the bottom, spreading a layer of melting covering flux on the crucible, covering the crucible cover, and turning over and melting; and remelting the mixture after 2 times of turnover, and cooling the mixture to obtain the lanthanum-rich rare earth magnesium alloy.
Example 5: aniline polymerization
5g of aniline is dissolved in 100mL of deionized water at 90 ℃, and the deionized water is dispersed for 5 minutes by ultrasonic vibration to obtain an aniline solution. Adding 2g of sodium persulfate into 50mL of 1M hydrochloric acid to dissolve to obtain an initiator solution, dropwise adding the initiator solution into the aniline solution, and heating to 90 ℃ at the heating rate of 1 ℃/min; after ultrasonic vibration dispersion for 30 minutes, aniline is polymerized to obtain a prepolymer, NaOH solution is added to adjust the pH value to be neutral, and polymerization is terminated to obtain micromolecular polyaniline which is dissolved in water; heating and evaporating to obtain a prepolymerization solution containing 5 wt% of polyaniline.
Example 6: modification of polyaniline
5g of aniline is dissolved in 100mL of deionized water at 90 ℃, and the deionized water is dispersed for 5 minutes by ultrasonic vibration to obtain an aniline solution. Adding 2g of sodium persulfate into 50mL of 1M hydrochloric acid to dissolve to obtain an initiator solution, dropwise adding the initiator solution into the aniline solution, and heating to 90 ℃ at the heating rate of 1 ℃/min; after ultrasonic vibration dispersion for 30 minutes, aniline is polymerized to obtain a prepolymer, NaOH solution is added to adjust the pH value to be neutral, and polymerization is terminated to obtain micromolecular polyaniline which is dissolved in water; heating and evaporating to obtain a prepolymerization solution containing 7.5 wt% of polyaniline.
Placing small pieces of metal magnesium and cerium-rich mischmetal (Mm) into a crucible, the bottom of which is paved with the melting covering flux obtained in example 1 according to the mol ratio of 10: 1 to form a material bed, paving a layer of melting covering flux on the material bed, covering a crucible cover, and placing the crucible cover into a well type furnace; heating to 800 deg.C at a speed of 10 deg.C/min, and maintaining for 1 hr; cooling to room temperature, turning over the sample, putting the sample in a crucible with the melting covering flux spread at the bottom, spreading a layer of melting covering flux on the crucible, covering the crucible cover, and turning over and melting; and remelting the mixture after 2 times of turnover, and cooling the mixture to obtain the cerium-rich rare earth magnesium alloy.
And (3) polishing the surface oxide skin of the massive rare earth magnesium alloy, filing 5g of rare earth magnesium alloy scraps by using a file, adding the polyaniline prepolymerization solution (100mL), stirring for reaction for 30min, filtering, and drying at the temperature of 80 ℃ to obtain the polyaniline modified cerium-rich mixed rare earth magnesium-based hydrogen storage material.
Example 7: polyaniline and Grignard reagent in situ modification
5g of aniline is dissolved in 100mL of deionized water at 90 ℃, and the deionized water is dispersed for 5 minutes by ultrasonic vibration to obtain an aniline solution. Adding 2g of sodium persulfate into 50mL of 1M hydrochloric acid to dissolve to obtain an initiator solution, dropwise adding the initiator solution into the aniline solution, and heating to 90 ℃ at the heating rate of 1 ℃/min; after ultrasonic vibration dispersion for 30 minutes, aniline is polymerized to obtain a prepolymer, NaOH solution is added to adjust the pH value to be neutral, and polymerization is terminated to obtain micromolecular polyaniline which is dissolved in water; heating and evaporating to obtain a prepolymer solution containing 10 wt% of polyaniline.
Placing small pieces of metal magnesium and metal cerium in a crucible, the bottom of which is paved with the smelting covering flux obtained in the example 1, according to the molar ratio of 12: 1 to form a material bed, paving a layer of smelting covering flux on the material bed, covering a crucible cover, and placing the crucible cover in a well type furnace; heating to 800 deg.C at a speed of 10 deg.C/min, and maintaining for 1 hr; cooling to room temperature, turning over the sample, putting it in a crucible with smelting covering flux on its bottom, and laying a layer of smelting flux on itSmelting and covering the flux, covering a crucible cover, and performing turnover smelting; remelting the mixture after 2 times of turnover, and cooling the mixture to obtain CeMg12Rare earth magnesium alloy.
Mixing the above blocks CeMg12Grinding off surface oxide skin, filing 5g of alloy scraps with a file, adding the polyaniline prepolymerization solution (100mL), stirring for reaction for 30min, filtering, and drying at 80 ℃ to obtain polyaniline-modified CeMg12。
1g of polyaniline modified CeMg12Placing the mixture into a reactor, dripping 5mL of tetrahydrofuran solution containing 1 wt% of fluorobenzene, connecting the reactor to a hydrogen absorption and desorption test system, heating to 70 ℃ for reaction for 2h, and then vacuumizing to obtain polyaniline and a Grignard reagent in-situ modified CeMg12Rare earth magnesium alloy.
Example 8: surface in-situ modification La2Mg17Hydrogen absorption of
The bulk La obtained in example 2 was taken2Mg17Grinding off surface oxide skin, filing 7.5g of alloy scraps by a file, adding the polyaniline pre-polymerization solution (100mL) obtained in example 5, stirring for reaction for 30min, filtering, and drying at 80 ℃ to obtain polyaniline-modified La2Mg17。
In the invention, the hydrogen absorption and desorption test system is a volumetric test system, namely the pressure change of each cavity with known volume is obtained through testing, and the hydrogen absorption and desorption amount of the material is obtained through calculation according to the mass conservation law and the gas state equation.
Taking 1g of polyaniline modified La2Mg17Placing the mixture into a reactor, dropwise adding 5mL of tetrahydrofuran solution containing 2.5 wt% of fluorobenzene, connecting the reactor to a hydrogen absorption and desorption test system, heating to 70 ℃ for reaction for 2h, vacuumizing the reactor to 1 pascal at 70 ℃, then filling hydrogen with the purity of 99.999% under 40 atmospheric pressure, heating to 200 ℃ at the speed of 5 ℃/min, and keeping the hydrogen pressure for 3 h to obtain the lanthanum-magnesium alloy hydride; similarly, metal magnesium is hydrogenated, and La with in-situ surface modification is adopted2Mg17The hydrogen absorption curve of magnesium powder from vendors is shown in FIG. 1. Compared with metal magnesium, the hydrogen absorption temperature is obviously reduced, and the hydrogen absorption speed is obviously improved.
In the invention, the lone pair electrons of nitrogen in aniline and rare earth in the rare earth magnesium alloy form coordination bonds. Since magnesium has no vacant d-orbital and f-orbital, nitrogen of aniline does not form a coordinate bond with magnesium, and polyaniline can be formed only in a region of a rare earth element. The rare earth is protected by polyaniline and can not react with fluorobenzene, and the fluorobenzene can only react with metal magnesium to form Grignard reagent phenylmagnesium fluoride. Thus, the rare earth magnesium alloy forms a composite surface film of polyaniline and phenylmagnesium fluoride in this hydrogen absorption scheme.
Example 9: surface in-situ modification CeMg12By discharging hydrogen
The bulk CeMg obtained in example 3 was taken12Grinding off surface oxide skin, filing 10g of alloy scraps by a file, adding the polyaniline pre-polymerization solution (100mL) obtained in example 5, stirring for reaction for 30min, filtering, and drying at 80 ℃ to obtain polyaniline-modified CeMg12。
1g of polyaniline modified CeMg12Placing the mixture into a reactor, dropwise adding 5mL of tetrahydrofuran solution containing 5 wt% of fluorobenzene, connecting the reactor to a hydrogen absorption and desorption test system, heating the mixture to 70 ℃ for reaction for 2h, vacuumizing the reactor to 1 pascal at 70 ℃, then filling hydrogen with the purity of 99.999% at 40 atmospheric pressure, heating the mixture to 200 ℃ at the speed of 5 ℃/min, and keeping the hydrogen pressure to ensure that the hydrogen storage capacity of the material reaches 6.5 wt%; similarly, commercial magnesium powder was hydrogenated to the same hydrogen storage capacity (6.5 wt%), hydrogen pressure was maintained at 1 atm (water and gas discharge method releases hydrogen to atmosphere), the temperature was raised to 400 ℃ at a rate of 5 ℃/min, and the hydrogen release curves of surface in situ modified cerium-magnesium alloy hydride and magnesium hydride are shown in FIG. 2. Compared with metal magnesium hydride, the hydrogen release temperature is obviously reduced at 220 ℃, the hydrogen release temperature of the metal magnesium hydride needs 380 ℃, and the hydrogen release speed of the cerium-magnesium alloy hydride with the surface modified in situ is obviously improved.
Finally, it should also be noted that the above-mentioned list is only a specific embodiment of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.