A metal aerogel catalyst, its preparation method and application

Abstract

This invention provides a metal aerogel catalyst, its preparation method, and its applications. The metal aerogel catalyst comprises a metal aerogel and heteroatoms doped within the metal aerogel; the metal aerogel comprises a metal and a carbon material coated on the metal; optionally, the carbon material contains nitrogen (N); wherein the metal is selected from one or more of Ni, Co, Mn, Cu, or Fe; and the heteroatoms are selected from one or more of N, P, S, B, or F. This invention utilizes the modification of the carbon material by heteroatoms and the enhanced electron transport properties with the active metal center to improve the activity of the catalytic material.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a metal aerogel catalyst, its preparation method, and its application. Background Technology

[0002] Selective hydrogenation refers to a reaction in which one functional group or substrate is preferentially converted while others remain unchanged when two or more functional groups coexist in a substrate or when different unsaturated substrates are present in the catalytic system. In the field of fine chemicals, when a substrate contains multiple functional groups, it is necessary to selectively reduce the target functional group while keeping other functional groups unchanged to synthesize fragrances, pesticides, pharmaceuticals, etc. Therefore, both bulk chemical and fine chemical production require efficient selective hydrogenation conversion, and the key lies in preparing highly efficient and selective catalysts.

[0003] Carbon materials have attracted widespread attention due to their excellent cost-effectiveness and outstanding stability. However, due to the lack of sufficient active sites, carbon materials often exhibit low catalytic activity in hydrogenation reactions. Therefore, heteroatoms (e.g., N, B, P, and S) can be doped into the carbon matrix to modulate its electronic structure. While heteroatomation itself has many advantages, they are prone to collapse and stacking during pyrolysis, which can adversely affect catalytic performance. Transition metals (e.g., Fe, Co, and Ni) have been shown to play important roles in selective hydrogenation.

[0004] Several research teams both domestically and internationally have conducted research on heteroatom-doped carbon-coated metallic materials. Patent CN116826024A discloses a doped porous hard carbon composite material, which achieves heteroatom doping by adding nitrogen- and / or phosphorus-containing melamine, phosphoric acid, urea, and pyrrole during the carbonization process. This method of adding external dopants has a wide range of applications; both metallic and non-metallic dopants can be used to prepare such materials (CN116854150A), making it the most commonly used heteroatom doping method. However, simple blending for doping may lead to uneven heteroatom distribution, and the content and form of heteroatoms are difficult to control. Therefore, some patents report the precise synthesis of heteroatom-containing precursors, followed by carbonization to obtain the corresponding heteroatom-doped carbon materials. Patent CN116715327A discloses an N, P, and B co-doped carbon material. They obtained a structurally well-defined organic polymer through a site-directed reaction of hexachlorocyclotriphosphazene with phenylenediboronic acid, followed by calcination at a constant temperature of 750℃ to obtain the heteroatom-doped carbon material. The heteroatom distribution in the material is uniform, and the doped structure is easily controllable. However, such methods often require complex organic synthesis reactions, especially since P and B-containing organic compounds are often extremely sensitive, have poor stability, and are costly, increasing the difficulty of material synthesis and application. Therefore, it is still necessary to develop a simple and efficient heteroatom doping method to achieve a uniform and controllable distribution of a series of heteroatoms. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a metal aerogel catalyst, its preparation method, and its applications. This invention utilizes the modification of carbon materials by heteroatoms and the enhanced electron transport properties with active metal centers to improve the activity of the metal aerogel catalyst. Simultaneously, controlling the type and content of heteroatoms adjusts the catalytic microstructure of the active metal center, thereby improving the selectivity of the metal aerogel catalyst in hydrogenation reactions.

[0006] In a first aspect, the present invention provides a metal aerogel catalyst comprising a metal aerogel and heteroatoms doped in the metal aerogel; the metal aerogel comprising a metal and a carbon material coated on the metal; optionally, the carbon material comprising N; wherein the metal is selected from one or more of Ni, Co, Mn, Cu or Fe; and the heteroatoms are selected from one or more of N, P, S, B or F.

[0007] Doping heteroatoms (e.g., N, B, P, and S) into a carbon matrix can modulate its electronic structure. Specifically, N doping generates more carbon charge sites (C+), the presence of which greatly promotes substrate adsorption and ultimately enhances catalytic activity. Furthermore, P, embedded in the carbon substrate, possesses a strong electron-donating ability, causing significant deformation of the carbon substrate and generating sufficient vacancies and defects. This facilitates substrate access to the metal active center and, through the introduction of channels, controls the substrate's approach, thereby further enhancing selective conversion.

[0008] In some embodiments, the heteroatom is selected from S and / or P.

[0009] In some embodiments, the total amount of the heteroatoms and N in the carbon material accounts for 0.5-15% of the mass of the metal aerogel catalyst, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value between them.

[0010] In some embodiments, the heteroatoms comprise 0.5-6% of the mass of the metal aerogel catalyst; for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, 6% or any value between them.

[0011] In some embodiments, the total amount of N in the carbon material accounts for 1-10% of the mass of the metal aerogel catalyst; for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value between them.

[0012] In some embodiments, the metal comprises 1-10% of the mass of the metal aerogel catalyst; for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value between them.

[0013] In some embodiments, when the heteroatom is P, the heteroatom accounts for 0.5-1.5% of the mass of the metal aerogel catalyst.

[0014] In some embodiments, the carbon material comprises carbon-containing substances formed by calcining biomass polysaccharides; preferably, the biomass polysaccharides are selected from one or more of chitosan, sodium alginate, glucose, bacterial cellulose, agarose, or hyaluronic acid.

[0015] In a second aspect, the present invention provides a method for preparing a metal aerogel catalyst, comprising the following steps:

[0016] (1) A hydrogel is formed by mixing an acidic aqueous solution containing biomass polysaccharides, an aqueous solution containing metal salts, and an alkaline solution containing heteroatoms.

[0017] (2) The hydrogel is calcined to obtain a metal aerogel catalyst.

[0018] In some embodiments, the method for preparing the hydrogel includes:

[0019] S1, mix an acidic aqueous solution containing biomass polysaccharides with an aqueous solution of metal salts to obtain a biomass polysaccharide-metal complex solution;

[0020] S2, add an alkaline solution containing heteroatoms dropwise to the polysaccharide-metal complex solution of the substance to obtain a hydrogel.

[0021] In some embodiments, the biomass polysaccharide is selected from one or more of chitosan, sodium alginate, glucose, bacterial cellulose, agarose, or hyaluronic acid. In some embodiments, the acidic aqueous solution is selected from one or more of formic acid aqueous solution, acetic acid aqueous solution, propionic acid aqueous solution, hydrochloric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, or nitric acid aqueous solution.

[0022] In some embodiments, the acidic aqueous solution containing biomass polysaccharides is a chitosan acetate aqueous solution.

[0023] Chitosan is the deacetylated form of the polysaccharide chitin, suitable for various soft materials, including aerogels. It is abundant, derived from waste materials in some marine industries, inexpensive, biocompatible, and soluble in weakly acidic solutions. It can readily form hydrogels with many metal salts, such as Pd, Pt, Au, Ag, Ni, and Co, under alkaline conditions, serving as a precursor for aerogels. When chitosan is chosen as the biomass polysaccharide, calcination of chitosan produces nitrogen atoms. This application, by introducing additional heteroatoms such as N, P, S, B, and F, can significantly promote substrate adsorption and ultimately enhance catalytic activity.

[0024] In some embodiments, the metal salt is selected from one or more of chlorides, acetates, nitrates, or acetylacetone salts containing Ni, Co, Mn, Cu, or Fe.

[0025] In some embodiments, the metal salt is selected from one or more of nickel chloride, nickel acetylacetonate, nickel acetate, nickel sulfate, nickel nitrate, ferric chloride, ferric nitrate, cobalt chloride, cobalt nitrate, or cobalt acetylacetonate.

[0026] In some embodiments, the alkaline solution containing heteroatoms is selected from one or more of the following: alkaline solution containing N, alkaline solution containing P, alkaline solution containing S, alkaline solution containing B, or alkaline solution containing F.

[0027] In some embodiments, the alkaline solution containing heteroatoms is selected from one or a combination of several of the following: ammonia, sodium or potassium amide, sodium or potassium fluoride, sodium or potassium phosphate, disodium or potassium hydrogen phosphate, sodium or potassium dihydrogen phosphate, sodium or potassium borate, sodium or potassium bisulfate, sodium or potassium sulfite, and sodium or potassium pyrosulfate.

[0028] Alkali solution directly participates in gel formation, dispersing uniformly throughout the gel network. Furthermore, by adding alkalis containing different heteroatoms and controlling their amounts, a series of controllable heteroatom doping can be achieved. Therefore, hydrogels with uniformly distributed heteroatoms can be prepared by adjusting the alkali content.

[0029] In some embodiments, when the alkaline solution is ammonia water, the ammonia water can be heated by steam to form ammonia gas, which then forms a hydrogel with the metal-biomass polysaccharide acid solution in the form of alkaline gas molecules. The N in the gel material is uniformly distributed and has excellent gelling properties.

[0030] In some embodiments, the concentration of biomass polysaccharides in the acidic aqueous solution is 1-100 g / L; for example, 5 g / L, 20 g / L, 35 g / L, 50 g / L, 65 g / L, 80 g / L, or 95 g / L.

[0031] In some embodiments, the concentration of biomass polysaccharides in the acidic aqueous solution is 10-50 g / L.

[0032] In some embodiments, the concentration of the biomass polysaccharide in the acidic aqueous solution is 20 g / L.

[0033] In some embodiments, the pH of the acidic aqueous solution is 0.1-5, for example, pH is 0.1, 0.5, 1, 2, 3, 4, 5.

[0034] In some embodiments, the pH of the acidic aqueous solution is 0.5-2.

[0035] In some embodiments, the pH of the acidic aqueous solution is 1.

[0036] In some embodiments, the concentration of the metal salt in the aqueous solution is 1-100 g / L, for example, 5 g / L, 20 g / L, 35 g / L, 50 g / L, 65 g / L, 80 g / L, or 95 g / L.

[0037] In some embodiments, the concentration of the alkaline solution is 0.1-10 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L.

[0038] In some embodiments, the concentration of the alkaline solution is 1-5 mol / L.

[0039] In some embodiments, the concentration of the alkaline solution is 2 mol / L.

[0040] In some embodiments, the volume ratio of the alkaline solution to the biomass polysaccharide-metal complex solution is 1:100-1:1, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, or 1:90.

[0041] In some embodiments, the volume ratio of the alkaline solution to the acidic aqueous solution of the biomass polysaccharide is 1:1 to 1:15.

[0042] In some embodiments, the volume ratio of the alkaline solution to the acidic aqueous solution of the biomass polysaccharide is 1:10.

[0043] In some embodiments, the molar ratio of the metal element in the biomass polysaccharide-metal complex solution to the heteroatoms in the alkaline solution is 0.1-10:1, for example, 1:1, 3:1, 5:1, 7:1, 9:1, etc.

[0044] In some embodiments, the molar ratio of the metal element in the biomass polysaccharide-metal complex solution to the heteroatoms in the alkaline solution is 0.1-2:1, for example, 0.1:1, 0.5:1, 0.7:1, 1:1, 1.2:1, 1.5:1, 1.7:1, 2:1 or any value between them, preferably 0.8-1.2:1.

[0045] In some embodiments, the mass ratio of the biomass polysaccharide to the metal salt is 1-100:1, for example, 10:1, 30:1, 50:1, 70:1, 90:1, 100:1, etc.

[0046] In some embodiments, the mass ratio of the biomass polysaccharide to the metal salt is 1-10:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or any value between them.

[0047] In some embodiments, the hydrogel is first frozen to obtain a dry gel before calcination; then the dry gel is freeze-dried.

[0048] In some embodiments, the hydrogel is frozen using a refrigerator.

[0049] In some embodiments, the freezing temperature is -30 to -90°C, for example -35°C, -40°C, -45°C, -50°C, -55°C, -60°C, -65°C, -70°C, -75°C, -80°C, -85°C, or -90°C.

[0050] In some embodiments, the freezing temperature is -30 to -80°C.

[0051] In some embodiments, the freezing temperature is -80°C.

[0052] In some embodiments, the freezing method is a gradient cooling, and the freezing cooling rate is 5-20℃ / hour, for example, 5℃ / hour, 7℃ / hour, 9℃ / hour, 11℃ / hour, 13℃ / hour, 15℃ / hour, 17℃ / hour, or 19℃ / hour.

[0053] In some embodiments, the freezing method is gradient cooling, and the freezing cooling rate is 5-10°C / hour.

[0054] In some embodiments, the freezing method is gradient cooling, and the freezing cooling rate is 10°C / hour.

[0055] In some embodiments, the dry gel is freeze-dried using a freeze dryer.

[0056] In some embodiments, the freeze-drying temperature is -30 to -60°C, for example -32°C, -34°C, -36°C, -38°C, -40°C, -42°C, -44°C, -46°C, -48°C, -50°C, -55°C, and -60°C.

[0057] In some embodiments, the freeze-drying temperature is -30 to -50°C.

[0058] In some embodiments, the freeze-drying temperature is -50°C.

[0059] In some embodiments, the freeze-drying time is 6-36 hours, for example 6 hours, 10 hours, 14 hours, 18 hours, 22 hours, 26 hours, 30 hours, or 34 hours.

[0060] In some implementations, the freeze-drying time is 10-15 hours.

[0061] In some implementations, the freeze-drying time is 12 hours.

[0062] In some embodiments, the calcination is carried out in a tube furnace.

[0063] In some embodiments, the calcination atmosphere is one or a combination of argon, nitrogen, and hydrogen.

[0064] In some embodiments, the calcination atmosphere is nitrogen.

[0065] In some embodiments, the calcination temperature is 350-800°C, for example 350°C, 400°C, 500°C, 600°C, 700°C, or 800°C.

[0066] In some embodiments, the calcination temperature is 350-500°C.

[0067] In some embodiments, the calcination temperature is 450°C.

[0068] In some embodiments, the calcination time is 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours or any value between them.

[0069] In some embodiments, the calcination heating rate is 1-5°C / minute.

[0070] In a third aspect, the present invention provides the application of the metal aerogel catalyst described in the first aspect of the present invention or the metal aerogel catalyst obtained by the preparation method described in the second aspect of the present invention in selective hydrogenation reactions.

[0071] In some embodiments, the selective hydrogenation reaction is selected from the selective half-hydrogenation of linalool, the selective half-hydrogenation of diphenylacetylene, the selective hydrogenation of p-nitrostyrene, or the selective synthesis of azo from nitrobenzene.

[0072] In some embodiments, the metal aerogel catalyst is directly recycled by magnetic attraction and applied to the next round of use without any additional activation steps.

[0073] In a fourth aspect, the present invention provides a selective hydrogenation reaction of dehydrolinalool, wherein dehydrolinalool is used as a raw material and reacted with hydrogen in the presence of a catalyst and a solvent; wherein the catalyst comprises the metal aerogel catalyst described in the first aspect or the metal aerogel catalyst obtained by the preparation method described in the second aspect.

[0074] In some embodiments, the reaction temperature is 50-90°C, for example 50°C, 60°C, 70°C, 80°C, 90°C or any value between them, preferably 60-80°C.

[0075] In some embodiments, the reaction temperature is 70°C.

[0076] In some embodiments, the pressure of the reaction is 2-10 atmospheres, for example, 2 atmospheres, 3 atmospheres, 4 atmospheres, 5 atmospheres, 6 atmospheres, 7 atmospheres, 8 atmospheres, 9 atmospheres, 10 atmospheres or any value therebetween, preferably 10 atmospheres.

[0077] In some embodiments, the reaction time is 5-20 hours, for example 5 hours, 7 hours, 9 hours, 11 hours, 13 hours, 15 hours, 17 hours, 19 hours or any value between them, preferably 5-10 hours.

[0078] In some implementations, the reaction time is 9 hours.

[0079] In some embodiments, the solvent is ethanol.

[0080] The present invention provides a method for preparing heteroatom-doped carbon-coated inexpensive metal catalytic materials based on hydrogels. The method involves dissolving a certain amount of chitosan in an acidic aqueous solution, stirring for a certain time, and then introducing an alkaline solution containing different heteroatoms to form a hydrogel. The hydrogel is then frozen in a refrigerator, freeze-dried in a freeze dryer, and calcined in a specific atmosphere to obtain a series of heteroatom-doped carbon-coated inexpensive metal aerogel catalytic materials.

[0081] In this invention, the acidic aqueous solution of chitosan is one of chitosan formic acid aqueous solution, acetic acid aqueous solution, propionic acid aqueous solution, hydrochloric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, and nitric acid aqueous solution, preferably chitosan acetic acid aqueous solution;

[0082] In this invention, the concentration of chitosan used is 1-100 g / L, preferably 20 g / L, and the pH of the acid solution is 1-5, preferably 1;

[0083] In this invention, the hydrogel is formed by passing an alkaline solution through a chitosan acid solution. The alkaline solution is one or a combination of several of the following: ammonia, sodium or potassium amide, sodium or potassium fluoride, sodium or potassium phosphate, disodium or potassium hydrogen phosphate, sodium or potassium dihydrogen phosphate, sodium or potassium borate, sodium or potassium bisulfate, sodium or potassium sulfite, and sodium or potassium pyrosulfate. By changing the type of heteroatom in the alkaline anion used, doping with a series of heteroatoms such as N, P, B, S, and F can be easily achieved.

[0084] The concentration of the alkaline solution used in this invention is 0.1-10 mol / L, preferably 2 mol / L, and the ratio of the alkaline solution to the chitosan acid solution is 1:100-1:1, preferably 1:10.

[0085] In this invention, when the alkaline solution used is ammonia water, ammonia water can be heated by steam to form ammonia gas, which then forms a hydrogel with the metal-chitosan acid solution in the form of alkaline gas molecules. The N in the gel material is uniformly distributed and has excellent gelling performance.

[0086] In this invention, the obtained hydrogel is placed in a refrigerator and frozen at a temperature of -30 to 80°C, preferably -80°C. The freezing method is a gradient cooling, freezing from room temperature to the desired temperature at a rate of 5-20°C / hour, preferably 10°C / hour.

[0087] In this invention, the frozen dry gel is freeze-dried in a freeze dryer at a temperature of -30 to 50°C, preferably -50°C, for a time of 6 to 36 hours, preferably 12 hours.

[0088] In this invention, the freeze-dried gel is placed in a tube furnace, and the gas atmosphere is one or a combination of argon, nitrogen, and hydrogen, preferably nitrogen. The calcination temperature is 350-800℃, preferably 450℃.

[0089] In this invention, after obtaining the heteroatom-doped aerogel catalytic material, its catalytic performance and stability for reuse were investigated in the selective semi-hydrogenation of dehydrolinalool, selective semi-hydrogenation of diphenylacetylene, selective hydrogenation of p-nitrostyrene, and selective synthesis of azo compounds from nitrobenzene. The reaction temperature was 70°C, the hydrogen pressure was 10 atm, the reaction solvent was ethanol, and the reaction time was 9 hours. The catalyst was recovered via magnetic adsorption and directly reused in the next round of applications without any additional activation steps.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] This invention prepares metal-chitosan hydrogels from biomass polysaccharides and common, inexpensive metal salts under the action of an alkali. By adjusting the type and amount of heteroatoms in the alkali, a series of carbon-coated inexpensive metal aerogel catalysts with different heteroatoms, such as N, P, B, S, and F, are achieved. The activity of the catalytic material is enhanced by utilizing the modification of carbon materials by heteroatoms and the enhanced electron transport properties with active metal centers. Simultaneously, controlling the type and content of heteroatoms adjusts the catalytic microstructure of the active metal centers, improving the selectivity of the material in hydrogenation reactions. This catalyst has the advantages of uniform heteroatom distribution, well-defined structure, and ease of control, resulting in highly dispersed coordinated active metal centers. When applied to selective hydrogenation, a widely used industrial reaction, this catalyst exhibits excellent catalytic performance. Furthermore, the activity and selectivity of the material can be controlled by simply adjusting the type and amount of alkali during hydrogel formation, facilitating further industrial applications.

[0092] The method of this invention is simple, widely applicable, and provides excellent and controllable doping effects. The prepared metal aerogel catalyst has a wide range of applications, requiring no additional dopants or complex organic synthesis. Various heteroatoms, such as N, P, B, S, and F, can be doped using this method, resulting in a uniform and easily tunable heteroatom distribution. This allows for precise control of the catalytic center microstructure, thereby improving its catalytic activity and selectivity. Furthermore, the anchoring effect of heteroatoms on the metal enhances the material's stability, enabling it to exhibit high efficiency in a series of selective hydrogenation reactions, thus demonstrating broad industrial application prospects. Attached Figure Description

[0093] Figure 1 (a) Ni catalyst obtained in Example 9 0.25 PXRD analysis results of @B2C-400 powder;

[0094] Figure 1 (b) Ni catalyst obtained in Example 8 0.25 Powder PXRD analysis results of @S2C-400;

[0095] Figure 1 (c) Ni catalyst obtained in Example 6 0.25 PXRD analysis results of P2C-400 powder;

[0096] Figure 1 (d) is a Ramen analysis result diagram of the catalysts obtained in Examples 6, 8 and 9;

[0097] Figure 2 The catalyst Ni obtained in Example 1 0.25 The X-ray photoelectron spectroscopy (XPS) analysis results of @N2C-400. Detailed Implementation

[0098] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0099] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0100] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0101] In this invention, room temperature refers to 20-30℃.

[0102] Example 1: Ni-doped Ni-based metal aerogel catalyst Ni 0.25 Preparation of @N2C-400:

[0103] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution with a pH of 1, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaNH2 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @N2C-400, where nitrogen atoms account for 4.85% of the total catalyst mass. The XPS of this catalyst is as follows: Figure 2 As shown.

[0104] Example 2: Ni-doped Ni-based metal aerogel catalyst Ni 0.5 Preparation of @N2C-400:

[0105] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (500 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaNH2 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.5 @N2C-400.

[0106] Example 3: Ni-doped Ni-based metal aerogel catalyst Ni 0.1 Preparation of @N2C-400:

[0107] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (100 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaNH2 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.1 @N2C-400.

[0108] Example 4: Ni-doped Ni-based metal aerogel catalyst Ni 0.25Preparation of @N1C-400:

[0109] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 1 mol / L NaNH2 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @N1C-400.

[0110] Example 5: Ni-doped Ni-based metal aerogel catalyst Ni 0.25 @N 10 Preparation of C-400:

[0111] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 10 mol / L NaNH2 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @N 10 C-400.

[0112] Example 6: P-doped Ni-based metal aerogel catalyst Ni 0.25 Preparation of @P2C-400:

[0113] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaH2PO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @P2C-400. The PXRD pattern of this catalyst is shown below. Figure 1 As shown in (c), the active phase is Ni.

[0114] Example 7: F-doped Ni-based metal aerogel catalyst Ni 0.25 Preparation of @F2C-400:

[0115] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The aqueous solution of nickel salt was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaF solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni.0.25 @F2C-400.

[0116] Example 8: S-doped Ni-based metal aerogel catalyst Ni 0.25 Preparation of @S2C-400:

[0117] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaHSO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @S2C-400. The PXRD pattern of this catalyst is shown below. Figure 1 As shown in (b), the active phase is Ni3S2.

[0118] Example 9: B-doped Ni-based metal aerogel catalyst Ni 0.25 Preparation of @B2C-400:

[0119] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L sodium borate solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @B2C-400. The PXRD pattern of this catalyst is shown below. Figure 1 As shown in (a), the active phase is Ni. Ramen analysis results of the catalysts obtained in Examples 6, 8, and 9 are shown in the following figures. Figure 1 As shown in (d).

[0120] Example 10

[0121] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (500 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaH2PO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.5 @P2C-400.

[0122] Example 11

[0123] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (100 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaH2PO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.1 @P2C-400.

[0124] Example 12

[0125] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 1 mol / L NaH2PO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @P1C-400.

[0126] Example 13

[0127] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved, yielding an acidic chitosan aqueous solution with a pH of 1. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water to obtain an aqueous solution of nickel salt. The nickel salt aqueous solution was slowly added dropwise to the acidic chitosan aqueous solution, and the resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex solution. 5 mL of the chitosan-Ni complex solution was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 10 mol / L NaH2PO4 solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @P 10 C-400.

[0128] Comparative Example 1

[0129] Chitosan (1.0 g) and water (50 mL) were added to a 100 mL round-bottom flask equipped with a magnetic stir bar. Then, 0.5 mL of glacial acetic acid was added, and the mixture was stirred at room temperature for two hours until the chitosan was completely dissolved. NiCl2·6H2O (250 mg) was dissolved in 4 mL of water, and the nickel salt solution was slowly added dropwise to the acidic chitosan solution. The resulting reaction system was stirred overnight at room temperature to obtain a synthesized chitosan-Ni complex. 5 mL of the chitosan-Ni complex was transferred to a 20 mL sample vial equipped with a magnetic stir bar, and 0.5 mL of 2 mol / L NaOH solution was slowly added dropwise under vigorous stirring. Hydrogel formation occurred, and stirring was stopped. The resulting hydrogel was frozen to -80 °C at a rate of 10 °C / hour, then placed in a freeze dryer and freeze-dried at -50 °C for 12 hours. The obtained powder was placed in a graphite boat and subjected to high-temperature pyrolysis in a tube furnace under a nitrogen atmosphere. The pyrolysis temperature program was to increase the temperature from room temperature to 400°C at a rate of 2°C per minute and hold at 400°C for 2 hours. The material obtained at a pyrolysis temperature of 400°C was labeled as Ni. 0.25 @C-400.

[0130] Application Example 1: The effect of different heteroatom-doped metal aerogel catalysts in the synthesis of linalool:

[0131] Dehydrolinalool (2 mmol, 304 mg), ethanol (10 mL), water (4 mL), and the metal aerogel catalyst prepared in Examples 1, 6-13, or the catalyst prepared in Comparative Example 1 were added to a tetrafluoroethylene liner equipped with a magnetic stirrer. The liner was then placed in an autoclave, and the autoclave was tightened. After purging the autoclave three times with hydrogen, it was filled with hydrogen at 10 atmospheres, and then the autoclave was placed in a 70°C oil bath and stirred for 9 hours. After the reaction was complete, the autoclave was cooled to room temperature, and the pressure was slowly released. The reaction yield was determined by GC and refined using the area normalization method. The results are shown in Table 1.

[0132] Table 1. Effects of different heteroatom-doped metal aerogel catalysts on linalool synthesis.

[0133]

[0134]

[0135] As shown in Table 1, heteroatoms have a significant impact on the reaction. P, due to its strong coordination ability and electron-donating effect, exhibits superior catalytic performance compared to N-doped aerogel materials, with a nearly 10% improvement in selectivity, demonstrating the feasibility of this strategy. S poisons the metal center, leading to a decrease in the activity of the resulting material, achieving only a 50% conversion rate. However, because S poisoning of the metal center further enhances its hydrogenation selectivity, the highest linalool selectivity (96%) can be obtained. B and F doping dopants do not significantly improve the selectivity of the material, and their doping effects are generally limited. In summary, P-doped catalysts achieve the highest yield in linalool production. In industrial production, product purification is a crucial step; therefore, it is necessary to further improve the selectivity of P-doped materials. By changing the metal and P content, the selectivity can be increased to 94%.

[0136] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the selective hydrogenation of dehydrolinalool, comprising reacting dehydrolinalool as a raw material with hydrogen in the presence of a catalyst and a solvent; wherein, The catalyst includes a metal aerogel catalyst, which comprises a metal aerogel and heteroatoms doped in the metal aerogel; the metal aerogel comprises a metal and a carbon material coated on the metal. The metal is selected from one or more of Ni, Co, Mn, Cu, or Fe; The heteroatoms are selected from S and / or P; The preparation method of the metal aerogel catalyst includes the following steps: (1) A hydrogel is formed by mixing an acidic aqueous solution containing biomass polysaccharides, an aqueous solution containing metal salts, and an alkaline solution containing heteroatoms; (2) The hydrogel is calcined to obtain a metal aerogel catalyst.

2. The method according to claim 1, characterized in that, The carbon material contains nitrogen (N).

3. The method according to claim 2, characterized in that, The total amount of heteroatoms and N in the carbon material accounts for 0.5-15% of the mass of the metal aerogel catalyst.

4. The method according to claim 1, characterized in that, The heteroatoms account for 0.5-6% of the mass of the metal aerogel catalyst.

5. The method according to claim 2, characterized in that, The total amount of nitrogen in the carbon material accounts for 1-10% of the mass of the metal aerogel catalyst.

6. The method according to claim 1, characterized in that, The metal accounts for 1-10% of the mass of the metal aerogel catalyst; The carbon material includes carbon-containing substances formed after calcination of biomass polysaccharides.

7. The method according to claim 1, characterized in that, The biomass polysaccharide is selected from one or more of chitosan, sodium alginate, glucose, bacterial cellulose, agarose, or hyaluronic acid.

8. The method according to claim 1, characterized in that, The method for preparing the hydrogel includes: S1, mix an acidic aqueous solution containing biomass polysaccharides with an aqueous solution of metal salts to obtain a biomass polysaccharide-metal complex solution; S2, an alkaline solution containing heteroatoms is added dropwise to the biomass polysaccharide-metal complex solution to obtain a hydrogel.

9. The method according to claim 1, characterized in that, The biomass polysaccharide is selected from one or more of chitosan, sodium alginate, glucose, bacterial cellulose, agarose, or hyaluronic acid; and / or The acidic aqueous solution is selected from one or more of formic acid aqueous solution, acetic acid aqueous solution, propionic acid aqueous solution, hydrochloric acid aqueous solution, sulfuric acid aqueous solution, phosphoric acid aqueous solution, or nitric acid aqueous solution; and / or The metal salt is selected from one or more of the following: chlorides, acetates, nitrates, or acetylacetone salts containing Ni, Co, Mn, Cu, or Fe.

10. The method according to claim 1, characterized in that, The metal salt is selected from one or more of nickel chloride, nickel acetylacetonate, nickel acetate, nickel sulfate, nickel nitrate, ferric chloride, ferric nitrate, cobalt chloride, cobalt nitrate, or cobalt acetylacetonate; and / or The alkaline solution containing heteroatoms is selected from one or more of the following: alkaline solutions containing P and alkaline solutions containing S.

11. The method according to claim 1, characterized in that, The alkaline solution containing heteroatoms is selected from one or a combination of several of the following: sodium or potassium phosphate, disodium or potassium hydrogen phosphate, sodium or potassium dihydrogen phosphate, sodium or potassium bisulfate, sodium or potassium sulfite, and sodium or potassium pyrosulfate aqueous solution.

12. The method according to claim 1, characterized in that, The concentration of the biomass polysaccharide in the acidic aqueous solution is 1-100 g / L; and / or The pH of the acidic aqueous solution is 0.1-5; and / or The concentration of the metal salt in the aqueous solution is 1-100 g / L.

13. The method according to claim 1, characterized in that, The concentration of biomass polysaccharides in the acidic aqueous solution is 10-50 g / L.

14. The method according to claim 1, characterized in that, The pH of the acidic aqueous solution is 0.5-2.

15. The method according to claim 8, characterized in that, The concentration of the alkaline solution is 0.1-10 mol / L; and / or The volume ratio of the alkaline solution to the biomass polysaccharide-metal complex solution is 1:100-1:1; and / or The mass ratio of the aqueous solution of the metal salt to the acidic aqueous solution of the biomass polysaccharide is 1:5-1:50; and / or The molar ratio of metal elements in the biomass polysaccharide-metal complex solution to heteroatoms in the alkaline solution is 0.1-10:1; and / or The mass ratio of the biomass polysaccharide to the metal salt is 1-100:

1.

16. The method according to claim 15, characterized in that, The concentration of the alkaline solution is 1-5 mol / L.

17. The method according to claim 15, characterized in that, The volume ratio of the alkaline solution to the biomass polysaccharide-metal complex solution is 1:1 to 1:

15.

18. The method according to claim 1, characterized in that, Before calcination, the hydrogel is first frozen to obtain a dry gel; then the dry gel is freeze-dried.

19. The method according to claim 18, characterized in that, The hydrogel was frozen using a refrigerator.

20. The method according to claim 18, characterized in that, The freezing temperature is -30 to -90°C.

21. The method according to claim 18, characterized in that, The freezing temperature is -30 to -80°C.

22. The method according to claim 18, characterized in that, The freezing method is gradient cooling, and the freezing cooling rate is 5-20℃ / hour.

23. The method according to claim 18, characterized in that, The freezing cooling rate is 5-10℃ / hour.

24. The method according to claim 18, characterized in that, The dry gel was freeze-dried using a freeze dryer.

25. The method according to claim 18, characterized in that, The freeze-drying temperature is -30 to -60°C.

26. The method according to claim 18, characterized in that, The freeze-drying temperature is -30 to -50°C; and / or the freeze-drying time is 6 to 36 hours.

27. The method according to claim 18, characterized in that, The freeze-drying time is 10-15 hours.

28. The method according to claim 1, characterized in that, The calcination is carried out in a tube furnace, and / or The calcination atmosphere is one or more of argon, nitrogen, and hydrogen; and / or The calcination temperature is 350-800℃; and / or The calcination time is 1-3 hours.

29. The method according to claim 1, characterized in that, The calcination temperature is 350-500℃.

30. The method according to claim 1, characterized in that, The heating rate of the calcination is 1-5℃ / minute.

31. The method according to claim 1, characterized in that, The reaction temperature is 50-90℃; and / or The reaction is performed at a pressure of 2-10 atmospheres; and / or The reaction time is 5-20 hours; and / or The solvent is ethanol.

32. The method according to claim 1, characterized in that, The reaction temperature is 60-80℃.

33. The method according to claim 1, characterized in that, The reaction was carried out at a pressure of 10 atmospheres.

34. The method according to claim 1, characterized in that, The reaction time is 5-10 hours.

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