Hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy as well as preparation method and application of hydrolysis hydrogen production material
By modifying low-quality waste magnesium alloys with low-temperature alloying, a layered Mg/Mg2Ca structure hydrolysis hydrogen production material was prepared, which solved the problems of difficult recycling of low-quality waste magnesium alloys and low efficiency of hydrolysis hydrogen production, and realized efficient hydrogen production and material recycling.
Patent Information
- Application Number
- CN202511114147.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-10-31
AI Technical Summary
Low-quality waste magnesium alloys are difficult to recycle, and the hydrolysis process of hydrolysis hydrogen production materials is easily interrupted by byproducts, resulting in low hydrogen conversion rate and slow reaction rate.
Low-quality scrap magnesium alloys were alloyed and modified. The high surface energy and small radius of curvature of nickel powder were used to smelt magnesium alloys at low temperature. Flux was added to protect and filter impurities, forming a lamellar structure of Mg2Ca and Mg phases, which promoted autocatalytic reaction and enhanced electrochemical corrosion. A Mg2Ni micro galvanic cell was prepared to accelerate the hydrolysis rate.
It achieves efficient reuse of low-quality waste magnesium alloys, with a hydrogen production conversion rate of over 90% through hydrolysis. The byproduct Mg(OH)2 can be reused, and the alloy can rapidly produce hydrogen at room temperature and pressure, making it suitable for industrial production.
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Figure CN120866701A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a hydrolytic hydrogen production material based on alloying modification of low-quality waste magnesium alloy, its preparation method and application, belonging to the technical field of hydrogen production materials and remelting and recycling of waste magnesium alloy. Background Technology
[0002] Magnesium alloys, as a high-performance metallic material, are widely used in various fields such as 3C, aerospace, and biomedicine. However, their production and use generate a large amount of secondary products and waste. In recent years, global magnesium alloy production has continued to grow, leading to a corresponding increase in the demand for recycled magnesium alloys. It is estimated that by 2025, the amount of recycled magnesium alloys will reach over 200,000 tons. While traditional magnesium alloy recycling technologies are relatively mature, bottlenecks remain, especially for low-quality magnesium alloys that are severely oxidized or corroded, contain dissimilar metals, heavy metal impurities, or organic pollutants. Magnesium alloys with a large surface coating of oxides (MgO) or deep corrosion face the critical problem of oxides entering the melt and forming slag phases during remelting and regeneration, reducing metal recovery rates and affecting melt flowability. Scrap materials containing elements such as Fe, Ni, and Cu, due to their high melting points and tendency to form hard and brittle intermetallic phases with magnesium, experience a sharp drop in strength after regeneration, requiring expensive processes such as vacuum sublimation for separation, which significantly increases equipment and energy costs. Machining debris or painted waste releases toxic fumes during smelting, while residual organic matter contaminates the melt. If the surface of the scrap has formed a thick oxide scale or is deeply corroded, the magnesium oxide will turn into slag after entering the molten pool, reducing metal yield and worsening fluidity. For smelting residues containing fluorides or silicates (such as Pidgeon process slag), their strong chemical inertness makes it difficult to extract valuable metals using conventional pyrometallurgical methods.
[0003] As a novel decentralized hydrogen source, metal hydrogen production materials can react with water to generate hydrogen under normal temperature and pressure conditions, directly supplying it to fuel cells and achieving on-demand hydrogen production without the need for storage and transportation. Magnesium, as a hydrogen production material, has advantages such as high electrochemical activity, high hydrogen production capacity, low cost, and no pollution. Under standard conditions, its theoretical hydrogen production capacity can reach 921 mL g. -1 However, the formation of dense, colloidal Mg(OH)2 byproducts on the Mg surface during hydrolysis is a key obstacle to achieving rapid hydrolysis and high hydrogen production rates in magnesium-based materials, resulting in low hydrogen conversion rates and slow reaction rates.
[0004] This invention uses low-quality scrap magnesium alloy as a matrix. Through alloying modification, the scrap magnesium alloy is smelted with high-melting-point nickel at a temperature far below nickel's melting point to prepare a cast magnesium alloy. Based on the optimization of the alloy's internal phase composition and microstructure, it achieves rapid hydrolysis for hydrogen production while simultaneously enabling the efficient reuse of the low-quality scrap magnesium alloy. Furthermore, the hydrolysis byproduct Mg(OH)₂ can be reused as a flame retardant, realizing efficient utilization of the magnesium alloy throughout its entire lifecycle. Summary of the Invention
[0005] The purpose of this invention is to address the key problems of the difficulty in recycling low-quality waste magnesium alloys and the easy interruption of the hydrolysis process of magnesium-based hydrolysis hydrogen production materials by being surrounded by by-products. The invention provides a magnesium-based material that can be prepared by remelting low-quality waste magnesium alloys at a lower temperature and can be rapidly hydrolyzed to produce hydrogen, with a hydrogen conversion rate of over 90%.
[0006] Meanwhile, this invention provides a method for preparing hydrolytic hydrogen production materials based on alloying modification of low-quality waste magnesium alloys. This method utilizes the high surface energy of nickel powder and the relationship between its solubility and radius of curvature, enabling the smelting of waste magnesium alloys and nickel at 730-750°C, a process with low energy consumption. The smelting process employs flux protection. The flux, through adsorption and surface tension, effectively filters impurities in the waste magnesium alloy. A small amount of unfiltered impurities can form defects in the cast alloy, serving as mass transfer points in the aqueous solution and accelerating the hydrolysis rate. Mg2Ca undergoes an autocatalytic reaction upon contact with water: Mg2Ca + 6H2O → 2Mg(OH)2 + Ca(OH)2 + 3H2↑, yielding a considerable hydrogen production rate. Its layered eutectic structure allows Mg and Mg2Ca to alternate, inhibiting the coating of dense hydroxides. Simultaneously, Mg2Ni, the matrix Mg, and Mg2Ca form a microscopic galvanic cell, significantly enhancing electrochemical corrosion and thus greatly improving the hydrogen production efficiency of the alloy through hydrolysis.
[0007] Meanwhile, this invention provides an application of a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy in fuel cells.
[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing hydrolysis hydrogen production materials based on alloying modification of low-quality waste magnesium alloys includes the following steps: Step 1: Press pure nickel powder into sheets at room temperature and mechanically crush it into small, long nickel strips. The nickel strips are 5-15 mm long, 1-3 mm wide, and 1-2 mm high. Step 2: Melt the low-quality scrap magnesium alloy, magnesium-calcium master alloy, and nickel bars in an electric resistance furnace at a melting temperature of 730~750°C, which is much lower than the melting point of nickel. (The amount of low-quality scrap magnesium alloy, magnesium-calcium master alloy, and nickel bars added should ensure that the mass fraction of calcium is 4%~12% and the mass fraction of nickel is 1%~3%).
[0009] Step 3: Pour the alloy melt into a preheated stainless steel mold, and remove the surface coating agent after demolding.
[0010] Preferably, low-quality scrap magnesium alloys include scrap containing heavy metals such as iron (Fe), nickel (Ni), and copper (Cu), machining waste or scrap parts with oil stains or paint coatings on the surface, scrap parts with a large amount of oxides (MgO) or deep corrosion on the surface, and smelting slag containing fluorides or silicates, which are difficult to smelt and recycle using conventional methods.
[0011] Preferably, the magnesium-calcium master alloy used is Mg-20Ca (wt.%) or Mg-30Ca (wt.%), and the nickel powder used is of industrial grade purity.
[0012] In step one, a fully automatic high-speed dual-pressure rotary tablet press is used to compress tablets at a pressure of 20~30MPa. The tablets are formed in one step without the need for pressure holding. The resulting material has a diameter of 12~15mm and a thickness of 1~2mm.
[0013] Preferably, in step two, the alloy preparation method is as follows: Weigh low-quality scrap magnesium alloy, magnesium-calcium intermediate alloy, and pressed nickel bars according to their mass ratio. Add an additional 5-10 wt.% magnesium to balance the burn-off during the smelting process. Then, place the raw materials in a graphite crucible, add RJ-6 flux to cover the metal, and heat in a resistance furnace to 730-750°C and hold for at least 30 minutes. During the holding period, stir thoroughly, with a 5-minute interval between each stirring. Then, pour the molten metal into a stainless steel mold to solidify. The mass ratio of the added RJ-6 flux to the smelted metal is (0.6-1.2):1. The flux is evenly sprinkled onto the metal surface before the smelting temperature rises, and then added in 2-5 batches as the temperature rises until the smelting is complete.
[0014] A hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy, comprising a cast alloy with a calcium mass fraction of 4%~12%, a nickel mass fraction of 1%~3%, and the balance being magnesium; the cast alloy consists of primary Mg and a eutectic structure, the eutectic structure being composed of two phases, Mg and Mg2Ca, which are alternately distributed in a lamellar shape; the cast alloy also contains a uniformly distributed Mg2Ni second phase.
[0015] A hydrogen production material based on alloying modification of low-quality waste magnesium alloy has been developed. The hydrogen production conversion rate is as high as 90.0% within 600 minutes. The hydrogen production capacity and rate of this hydrogen production material are comparable to those of new magnesium alloy.
[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention uses low-quality waste magnesium alloy, nickel powder, and magnesium-calcium master alloy as raw materials. By utilizing the high surface energy and small radius of curvature of nickel powder, the alloy can be prepared by alloying and melting at temperatures below 750°C, resulting in low energy consumption. Flux protection can effectively adsorb impurities in the low-quality waste magnesium alloy. Due to the small size of the nickel powder, the Mg2Ni second phase in the prepared alloy is also small and uniformly distributed, forming a large number of micro-galvanic cells with the Mg and Mg2Ca phases in the cast alloy. This alloy can continuously produce hydrogen in water, and the by-products magnesium hydroxide and calcium hydroxide are non-toxic and harmless. Its layered Mg / Mg2Ca structure promotes the self-peeling of the passivation film, thereby significantly accelerating hydrolysis and increasing the hydrogen yield, realizing rapid and continuous hydrolysis of the block alloy to produce hydrogen, and realizing the recycling of magnesium throughout its entire life cycle.
[0017] (2) The block alloy obtained by the present invention can be stored and transported stably and safely, and can react rapidly with aqueous solution to produce hydrogen. The by-product Mg(OH)2 can be reused as a flame retardant.
[0018] (3) The preparation process of this invention is simple and inexpensive, and it is suitable for large-scale production.
[0019] In summary, the preparation process of this invention is simple, low-cost, and time-saving. This composite material can rapidly produce large quantities of hydrogen with a high conversion rate, making it suitable for industrial production. Attached Figure Description
[0020] Figure 1 This is a SEM image of the alloy microstructure of Example 1 of the present invention; Figure 2 The kinetic curve of hydrogen production by reacting the as-cast alloy obtained in Example 1 of the present invention with seawater at room temperature and pressure is shown. Figure 3 This is a SEM image of the alloy microstructure of Example 2 of the present invention; Figure 4 The kinetic curve of hydrogen production by reacting the as-cast alloy obtained in Example 2 of this invention with seawater at room temperature and pressure is shown. Figure 5 This is a SEM image of the alloy microstructure of Example 3 of the present invention; Figure 6 This is the kinetic curve of hydrogen production by reacting the as-cast alloy obtained in Example 3 of the present invention with seawater at room temperature and pressure. Detailed Implementation
[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1
[0022] A method for preparing hydrolytic hydrogen production material based on alloying modification of low-quality waste magnesium alloy includes the following steps: using a fully automatic high-speed dual-pressure rotary tablet press to press industrial pure nickel powder into tablets at room temperature at a pressure of 20 MPa, forming tablets in one step without holding pressure, the resulting material has a diameter of 12 mm and a thickness of 1.2 mm, and is mechanically crushed into small long strips of nickel with a length of 5 mm, a width of 1 mm, and a height of 1.2 mm. Low-quality scrap AZ91D magnesium alloy from machining was mixed with magnesium-calcium master alloy (Mg-20wt.%Ca) and small nickel bars in a specific ratio, with Ca accounting for 8% of the mass and Ni for 1.5%. An additional 5% of magnesium was added to balance burn-off and oxidation during the smelting process. The resulting metal raw material blocks were then placed in a graphite crucible, and RJ-6 flux was added (the mass ratio of RJ-6 flux to the smelting metal was 0.9:1). The RJ-6 flux was evenly sprinkled onto the metal surface before heating and then added as the temperature increased. The flux was added in three batches as the temperature increased until the smelting was completed (each batch containing an equal amount of RJ-6 flux). The metal was then covered and heated in a resistance furnace to 750°C, held for 30 minutes, and stirred thoroughly with 5-minute intervals between each stirring to create a macroscopically homogeneous melt. The molten metal was then poured into a stainless steel mold to solidify. The surface covering and oxide layer were then removed. The alloy consists of primary Mg and a eutectic structure. The eutectic structure is composed of two phases, Mg and Mg₂Ca, which are alternately distributed in a lamellar pattern. Its SEM microstructure is shown below. Figure 1 As shown.
[0023] Figure 2 The phenomenon of hydrogen production by reacting the prepared cast alloy with seawater at room temperature and pressure and the kinetic curve of hydrogen production by hydrolysis were shown. The hydrogen production of the prepared composite material can reach 799.3 mL / g within 600 min, with a conversion rate as high as 93.6%.
[0024] This embodiment yields a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy, comprising a cast alloy with a calcium content of 8%, a nickel content of 1.5%, and the balance being magnesium.
[0025] The hydrogen production material obtained in this embodiment, based on the alloying modification of low-quality waste magnesium alloy, has a hydrogen production conversion rate of up to 93.6% within 600 minutes.
[0026] This embodiment presents an application of a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy in a fuel cell. Example 2
[0027] A method for preparing hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy includes the following steps: using a fully automatic high-speed dual-pressure rotary tablet press to press industrial pure nickel powder into tablets at room temperature, with a pressure of 25 MPa, forming tablets in one step without holding pressure, the resulting material has a diameter of 13 mm and a thickness of 1.0 mm, and is mechanically crushed into small long nickel strips with a length of 10 mm, a width of 2 mm, and a height of 1.0 mm; Low-quality scrap AZ31 magnesium alloy that has undergone deep corrosion is mixed with magnesium-calcium master alloy (Mg-20wt.%Ca) and small nickel bars in a certain proportion, where the mass fraction of Ca is 4% and the mass fraction of Ni is 3%. An additional 5% of magnesium is added to balance the burn-off and oxidation during the smelting process. The above metal raw material blocks are then placed in a graphite crucible, and RJ-6 flux is added (the mass ratio of RJ-6 flux to the mass of the smelting metal is 0.6:1, and the RJ-6 flux is evenly sprinkled on the metal surface before the smelting temperature rises). The flux was added in two batches as the temperature rose until the melting was complete (each batch containing an equal amount of RJ-6 flux) to cover the metal. The metal was then heated to 730°C in a resistance furnace and held for 40 minutes, stirring thoroughly during the holding period to ensure a macroscopically homogeneous melt. The molten metal was then poured into a stainless steel mold to solidify. The surface coating and oxide layer were then removed. The alloy consists of primary Mg and a eutectic structure. The eutectic structure is composed of two phases, Mg and Mg₂Ca, which are alternately distributed in a lamellar pattern. Its SEM microstructure is shown in the image. Figure 3 As shown.
[0028] Figure 4 The phenomenon of hydrogen production by reacting the prepared as-cast alloy with seawater at room temperature and pressure and the kinetic curve of hydrogen production by hydrolysis were shown. The prepared composite material can produce 883.7 mL / g of hydrogen within 600 min, with a conversion rate as high as 94.1%.
[0029] This embodiment yields a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy, which is a cast alloy with a calcium content of 4% by mass, a nickel content of 3% by mass, and the balance being magnesium.
[0030] The hydrogen production material obtained in this embodiment, based on the alloying modification of low-quality waste magnesium alloy, has a hydrogen production conversion rate of up to 94.1% within 600 minutes.
[0031] This embodiment presents an application of a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy in a fuel cell. Example 3
[0032] A method for preparing hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy includes the following steps: using a fully automatic high-speed dual-pressure rotary tablet press to press industrial pure nickel powder into tablets at room temperature, with a pressure of 30 MPa, forming tablets in one step without holding pressure, the resulting material has a diameter of 15 mm and a thickness of 2 mm, and is mechanically crushed into small long strips of nickel with a length of 15 mm, a width of 3 mm, and a height of 2.0 mm. Low-quality WE43 magnesium alloy scrap with oil stains and paint coatings on the surface was mixed with magnesium-calcium master alloy (Mg-30wt.%Ca) and small nickel bars in a certain proportion, with Ca accounting for 12% of the mass and Ni accounting for 1% of the mass. An additional 10% of magnesium was added to balance the burn-off and oxidation during the smelting process. The above metal raw material blocks were then placed in a graphite crucible, and RJ-6 flux was added (the mass ratio of RJ-6 flux to the mass of the smelting metal was 1.2:1, and the RJ-6 flux was evenly sprinkled on the surface before the smelting temperature was raised). The metal surface was then covered with RJ-6 flux (added in five batches at a time, with each batch containing an equal amount of flux) as the temperature increased. The metal was then heated to 730°C in a resistance furnace and held for 30 minutes, stirring thoroughly during this period to ensure a macroscopically homogeneous melt. The molten metal was then poured into a stainless steel mold to solidify. The surface coating and oxide layer were then removed. The alloy consists of primary Mg and a eutectic structure. The eutectic structure comprises two phases, Mg and Mg₂Ca, which are alternately distributed in a lamellar pattern. Its SEM microstructure is shown in the image. Figure 5 As shown.
[0033] Figure 6 The phenomenon of hydrogen production by reacting the prepared as-cast alloy with seawater at room temperature and pressure and the kinetic curve of hydrogen production by hydrolysis were shown. The hydrogen production of the prepared composite material can reach 801.5 mL / g within 600 min, with a conversion rate as high as 90.6%.
[0034] This embodiment yields a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy, which is a cast alloy with a calcium content of 12% by mass, a nickel content of 1% by mass, and the balance being magnesium.
[0035] The hydrogen production material obtained in this embodiment, based on the alloying modification of low-quality waste magnesium alloy, has a hydrogen production conversion rate of up to 90.6% within 600 minutes.
[0036] This embodiment presents an application of a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy in a fuel cell.
[0037] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.
[0038] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.
[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy, characterized in that, The as-cast alloy comprises 4% to 12% calcium, 1% to 3% nickel, and the balance magnesium. The as-cast alloy consists of primary Mg and a eutectic structure. The eutectic structure consists of two phases, Mg and Mg2Ca, which are distributed alternately in a lamellar manner. The as-cast alloy also contains a uniformly distributed Mg2Ni second phase.
2. The hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy according to claim 1, characterized in that, The hydrogen production conversion rate of the as-cast alloy is as high as 90.0% or more within 600 minutes.
3. The hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy according to claim 1, characterized in that, Low-quality scrap magnesium alloys include scrap containing heavy metal elements, machining waste or scrap parts with oil stains or paint coatings on the surface, scrap parts with oxides or corrosion on the surface, and scrap magnesium alloys containing fluoride or silicate slag.
4. The hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy according to claim 3, characterized in that, Heavy metals include iron, nickel, and copper; oxides include MgO.
5. A method for preparing a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Press pure nickel powder into sheets at room temperature and mechanically crush it into small, long nickel strips; Step 2: Weigh the low-quality scrap magnesium alloy, magnesium-calcium master alloy, and nickel bars according to the mass ratio, and add an additional 5-10 wt.% magnesium. Place the raw materials in a graphite crucible, add some RJ-6 flux to cover the raw materials, and then heat in a resistance furnace to 730-750°C and hold for at least 30 minutes. Stir thoroughly during the holding period, with each stirring interval of 5 minutes. The mass ratio of the added RJ-6 flux to the mass of the raw materials is (0.6-1.2):
1. The RJ-6 flux is evenly sprinkled on the surface of the raw materials before the melting temperature rises, and then added in 2-5 batches as the temperature rises until the melting is completed to obtain the alloy melt. Step 3: Pour the alloy melt into a stainless steel mold, and remove the surface coating after demolding.
6. The preparation method according to claim 5, characterized in that, In step one, the pressure of tableting is 20~30MPa, and tableting is performed in one step without holding pressure. The diameter of the pressed material is 12~15mm and the thickness is 1~2mm.
7. The preparation method according to claim 5, characterized in that, In step one, the nickel bar has a length of 5~15mm, a width of 1~3mm, and a height of 1~2mm.
8. The preparation method according to claim 5, characterized in that, In step two, the magnesium-calcium master alloy is Mg-20Ca or Mg-30Ca.
9. A hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy obtained by the preparation method according to claim 5, characterized in that, The hydrogen production capacity and rate of this hydrolysis hydrogen production material are comparable to those of the new magnesium alloy.
10. The application of a hydrolysis hydrogen production material based on alloying modification of low-quality waste magnesium alloy as described in any one of claims 1 to 4 in a fuel cell.