CN112755994A - Carbon-coated nickel-aluminum nano composite material and preparation method and application thereof - Google Patents

Carbon-coated nickel-aluminum nano composite material and preparation method and application thereof Download PDF

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CN112755994A
CN112755994A CN201911001564.6A CN201911001564A CN112755994A CN 112755994 A CN112755994 A CN 112755994A CN 201911001564 A CN201911001564 A CN 201911001564A CN 112755994 A CN112755994 A CN 112755994A
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nickel
aluminum
carbon
temperature
salt
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于鹏
荣峻峰
宗明生
谢婧新
林伟国
吴耿煌
纪洪波
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Priority to CN201911001564.6A priority Critical patent/CN112755994A/en
Priority to JP2022523622A priority patent/JP2022553343A/en
Priority to EP20880137.3A priority patent/EP4049752A4/en
Priority to US17/755,112 priority patent/US20220370989A1/en
Priority to PCT/CN2020/122099 priority patent/WO2021078113A1/en
Priority to TW109136552A priority patent/TW202116414A/en
Publication of CN112755994A publication Critical patent/CN112755994A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/74—Iron group metals
    • B01J23/755—Nickel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/396—Distribution of the active metal ingredient
    • B01J35/398—Egg yolk like
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/30—Improvements relating to adipic acid or caprolactam production

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Abstract

The invention provides a carbon-coated nickel-aluminum nano composite material, a preparation method and application thereof, wherein the nano composite material comprises a nuclear membrane structure with an outer membrane and an inner core, the outer membrane is a graphitized carbon membrane, and the inner core comprises nickel oxide and aluminum oxide, wherein the total mass of the nano composite material is taken as a reference, the content of nickel oxide is 59% -80%, the content of aluminum oxide is 19% -40%, and the content of carbon is not more than 1%. The nano composite material has novel and unique structure, has great application potential in catalytic materials, energy storage materials and electromagnetic materials, has excellent activity when being used as a catalyst, can effectively catalyze and decompose nitrous oxide, and is beneficial to solving the problem of high concentration generated in the production processes of adipic acid plants, nitric acid plants and the likeN2The elimination of the O waste gas has important significance for protecting the environment and reducing the atmospheric pollution, and has good industrial application prospect.

Description

Carbon-coated nickel-aluminum nano composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of catalysis, in particular to a carbon-coated nickel-aluminum nano composite material and a preparation method and application thereof.
Background
The transition metal oxide has excellent catalytic performance and electromagnetic performance, is a research hotspot in the field of inorganic materials, and has wide application in energy storage materials, catalytic materials, magnetic recording materials and biological medicines. The carbon material has good conductivity, good chemical/electrochemical stability and high structural strength. The nano particles of active metal or metal oxide are coated by carbon material, which can effectively improve the conductivity and stability of the nano catalyst, and has limited action on the nano particles, so that the nano catalyst is not easy to agglomerate. In recent years, carbon-coated nanomaterials are widely applied to the fields of electrocatalysis, supercapacitor materials, lithium ion battery negative electrode materials, bioengineering and the like.
Nitrous oxide (N)2O) is an important greenhouse gas, whose Global Warming Potential (GWP) is CO2310 times of, CH421 times of the total weight of the composition; furthermore, N2The average life of O in the atmosphere is about 150 years, and the O is also a main source of NOx in the stratosphere, not only can seriously damage the ozone layer, but also has strong greenhouse effect.
Domestic lifeThe method for producing adipic acid mainly adopts a cyclohexanol nitric acid oxidation method, and the cyclohexanol is oxidized by nitric acid to produce adipic acid, the method has mature technology, the product yield and purity are higher, but the nitric acid consumption is large, and a large amount of N is produced in the reaction process2And the tail gas discharged in the production process is concentrated, large in quantity and high in concentration (30% -40%). At present, 15 ten thousand tons of adipic acid and N are produced annually by a nitric acid oxidation method of cyclohexanol2The annual emission of O can reach 4.5 ten thousand tons. Therefore, the tail gas of the adipic acid device is purified, and N is effectively controlled and eliminated2O has become a research hotspot in the field of environmental catalysis at present.
By direct catalytic decomposition of N2O is decomposed into nitrogen and oxygen to eliminate N2O is the most efficient and clean technique. Among them, the catalyst is the core of the direct catalytic decomposition method. Decomposition of N reported in the present study2The catalyst of O mainly comprises noble metal catalyst, ion-exchanged molecular sieve catalyst and transition metal oxide catalyst. Noble metal catalysts (e.g., Rh and Ru) vs. N2The O catalytic decomposition has higher low-temperature catalytic activity (within the range of 250-350 ℃) and can efficiently decompose N2O), but the expensive price limits the large-scale application of noble metal catalysts. The price of molecular sieve catalyst and transition metal oxide catalyst is obviously lower than that of noble metal, but at present, the two catalysts are used for N2The activity of O catalytic decomposition is low, the temperature range of efficient decomposition is 450-550 ℃, and the decomposition can be carried out only by diluting high-concentration laughing gas to about 0.5-2% concentration, thereby greatly improving the industrial cost.
Therefore, the catalyst pair N with low development cost and high activity2The emission reduction of O has important significance.
It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
It is a primary object of the present invention to overcome at least one of the above-mentioned disadvantages of the prior art and to provide a carbon-coated nickel-aluminum nanocomposite and a method for preparing the sameThe nano composite material contains a nuclear membrane structure with a graphitized carbon membrane and nickel oxide and aluminum oxide cores, has excellent activity as a catalyst, can effectively catalyze and decompose nitrous oxide, and is beneficial to solving the problem of high-concentration N generated in the production processes of adipic acid plants, nitric acid plants and the like2The elimination of the O waste gas has important significance for protecting the environment and reducing the atmospheric pollution, and has good industrial application prospect.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a carbon-coated nickel-aluminum nanocomposite, which comprises a nuclear membrane structure with an outer membrane and an inner core, wherein the outer membrane is a graphitized carbon membrane, and the inner core comprises nickel oxide and aluminum oxide, wherein the nickel oxide content is 59% -80%, the aluminum oxide content is 19% -40%, and the carbon content is not more than 1% based on the total mass of the nanocomposite.
According to one embodiment of the invention, the nickel oxide content is 69% to 79%, the alumina content is 20% to 30%, and the carbon content is 0.3% to 1%.
According to one embodiment of the present invention, the ratio of the carbon element in the nanocomposite material as determined by X-ray photoelectron spectroscopy to the carbon element content as determined by elemental analysis is not less than 10 in terms of mass ratio.
According to one embodiment of the invention, the Raman spectrum of the nanocomposite material is at 1580cm-1Intensity of nearby G peak at 1320cm-1The ratio of the intensities of the nearby D peaks is greater than 2.
According to one embodiment of the invention, the particle size of the nuclear membrane structure is between 2nm and 100 nm.
According to one embodiment of the invention, the inner core further comprises an alkali metal oxide, the content of alkali metal oxide in mass percent in the nanocomposite material being not more than 5%, preferably not more than 2.5%.
The second aspect of the present invention provides a method for preparing the carbon-coated nickel-aluminum nanocomposite, comprising the following steps: preparing a nickel-aluminum precursor; carrying out heating treatment on the nickel-aluminum precursor, and carrying out vapor deposition by taking low-carbon alkane as a carbon source gas; and carrying out oxygen treatment on the product after vapor deposition to obtain the nano composite material.
According to one embodiment of the invention, the oxygen treatment comprises introducing standard gas into the product after vapor deposition and heating, wherein the standard gas comprises oxygen and balance gas, and the volume concentration of the oxygen is 10-40%.
According to one embodiment of the present invention, the temperature of the oxygen treatment is 200 ℃ to 500 ℃ and the time of the oxygen treatment is 0.5h to 10 h.
According to one embodiment of the present invention, the manner of preparing the nickel aluminum precursor is coprecipitation and/or hydrothermal crystallization.
According to one embodiment of the present invention, the step of preparing the nickel aluminum precursor comprises: simultaneously dripping alkali liquor and aqueous solution containing trivalent aluminum salt and divalent nickel salt into water for precipitation treatment to enable trivalent aluminum salt and divalent nickel salt to generate coprecipitate; and aging the coprecipitate.
According to one embodiment of the invention, the trivalent aluminum salt comprises aluminum nitrate and/or aluminum chloride, the divalent nickel salt comprises nickel nitrate and/or nickel chloride, and the molar ratio of aluminum in the trivalent aluminum salt to nickel in the divalent nickel salt is 1: (2-4); the alkali liquor is an aqueous solution containing sodium hydroxide and sodium carbonate, the concentration of the sodium hydroxide in the alkali liquor is 0.2-4 mol/L, and the concentration of the sodium carbonate is 0.1-2 mol/L; the ratio of the mole number of the sodium hydroxide to the total mole number of the aluminum and the nickel in the trivalent aluminum salt and the divalent nickel salt is (2-4): 1, the ratio of the mole number of the sodium carbonate to the total mole number of the aluminum and the nickel in the trivalent aluminum salt and the divalent nickel salt is (0.5-2): 1.
according to one embodiment of the present invention, the precipitation treatment temperature is 40 ℃ to less than 100 ℃, the aging treatment temperature is 40 ℃ to less than 100 ℃, and the aging treatment time is 2 to 48 hours.
According to one embodiment of the invention, the method further comprises the step of contacting the nickel-aluminum precursor subjected to temperature-raising heat treatment with hydrogen to perform reduction treatment, wherein the temperature of the reduction treatment is 500-900 ℃, the time is 120-480 min, and the hydrogen flow is 30-50 ml/(min. g nickel-aluminum precursor).
According to one embodiment of the invention, the method further comprises the steps of mixing a nickel-aluminum precursor with a salt solution of alkali metal for coprecipitation reaction, and then heating the obtained precipitate, wherein the molar ratio of the alkali metal to the nickel is not more than 0.2.
According to one embodiment of the invention, the heating treatment comprises heating the nickel-aluminum precursor to 500-900 ℃ under the condition of introducing protective gas, wherein the protective gas is nitrogen and/or argon, the flow rate of the protective gas is 10-500 ml/(min. g nickel-aluminum precursor), and the heating speed is 1-5 ℃/min; the temperature of vapor deposition is 750-900 ℃, preferably 780-850 ℃, the time of vapor deposition can be 5-240 minutes, and the flow of carbon source gas is 10-500 ml/(min. g nickel/aluminum precursor); preferably, the time is 60 to 120 minutes, and the flow rate of the carbon source gas is 30 to 100 ml/(min. g nickel-aluminum precursor). The carbon source gas is methane or ethane.
A third aspect of the present invention provides the use of the above nanocomposite as a catalytic material, an energy storage material or an electromagnetic material.
A fourth aspect of the present invention provides the use of the above nanocomposite as a catalyst for the decomposition of nitrous oxide, comprising: the catalyst is contacted with nitrous oxide to carry out catalytic decomposition reaction to generate nitrogen and oxygen.
According to one embodiment of the present invention, the temperature of the catalytic decomposition reaction is 300 ℃ to 400 ℃.
According to one embodiment of the invention, the space velocity of the catalytic decomposition reaction is 1000h-1～3000h-1。
According to one embodiment of the invention, the nitrous oxide has a volume concentration comprised between 30% and 40%.
According to the technical scheme, the carbon-coated nickel-aluminum nano composite material, the preparation method and the application have the advantages and positive effects that:
the carbon-coated nickel-aluminum nanocomposite provided by the invention comprises a nuclear membrane structure with a graphitized carbon membrane and nickel oxide and aluminum oxide cores, and is formed by unique junctionsHaving a composition such that it catalyzes N as a catalyst2Has excellent activity in O decomposition reaction, and compared with the prior catalyst, the catalyst has the advantage that N in industrial waste gas must be added2The catalyst can be used for catalytically decomposing high-concentration nitrous oxide waste gas generated in industrial production at a lower temperature, the decomposition rate can reach more than 99 percent, and the catalyst has important significance for protecting the environment and reducing the atmospheric pollution and has good industrial application prospect.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is an X-ray diffraction pattern of the nanocomposite of example 1;
FIGS. 2a and 2b are transmission electron microscope images of the nanocomposite material of example 1 at different magnifications, respectively;
FIG. 3 is a Raman spectrum of the nanocomposite material of example 1;
FIG. 4 is an X-ray diffraction pattern of the nanocomposite material of example 2;
FIGS. 5a and 5b are transmission electron microscope images of the nanocomposite material of example 2 at different magnifications, respectively;
FIG. 6 is a Raman spectrum of the nanocomposite material of example 2.
Detailed Description
The following presents various embodiments or examples in order to enable those skilled in the art to practice the invention with reference to the description herein. These are, of course, merely examples and are not intended to limit the invention. The endpoints of the ranges and any values disclosed in the present application are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to yield one or more new ranges of values, which ranges of values should be considered as specifically disclosed herein.
Any terms not directly defined herein should be understood to have meanings associated with them as commonly understood in the art of the present invention. The following terms as used throughout this specification should be understood to have the following meanings unless otherwise indicated.
The term "nuclear membrane structure" in the present invention means a nuclear membrane structure having an outer membrane which is a graphitized carbon membrane and an inner core comprising nickel oxide and aluminum oxide nanoparticles. The composite material formed after the graphitized carbon film is coated with nickel oxide and aluminum oxide nano particles is spherical or quasi-spherical.
The term "graphitized carbon film" refers to a thin film structure composed mainly of graphitized carbon.
The term "carbon element content determined by X-ray photoelectron spectroscopy" refers to the relative content of carbon elements on the surface of a material measured by quantitative elemental analysis using an X-ray photoelectron spectrometer as an analysis tool.
The term "carbon content determined in elemental analysis" refers to the relative content of total carbon elements of a material measured by elemental quantitative analysis using an elemental analyzer as an analysis tool.
The first aspect of the invention provides a carbon-coated nickel-aluminum nanocomposite, which comprises a core film structure with an outer film and an inner core, wherein the outer film is a graphitized carbon film, and the inner core comprises nickel oxide and aluminum oxide, wherein the nickel oxide content is 59% -80%, the aluminum oxide content is 19% -40%, and the carbon content is not more than 1% based on the total mass of the nanocomposite. In some embodiments, the nickel oxide content is 69% to 79%, the alumina content is 20% to 30%, and the carbon content is 0.3% to 1%.
According to the present invention, the carbon-coated nickel-aluminum nanocomposite is a core film structure comprising an outer film layer and an inner core layer, wherein the outer film layer is mainly composed of a graphitized carbon film, and the inner core comprises nickel oxide and aluminum oxide. The graphitized carbon film is a thin film structure mainly composed of graphitized carbon and is coated on the surfaces of nickel oxide and aluminum oxide nano particles. The inventor of the invention unexpectedly finds that the nuclear membrane structure coated with the graphitized carbon membrane on the outer layer has relatively little carbon content in the thin membrane layer, but greatly improves the performance of the whole material, particularly the catalytic performance, specifically, the nuclear membrane structure not only can generate a certain limited domain effect, effectively avoids the aggregation and growth of nickel oxide and alumina nano particles in a core, enables the catalytic activity of the composite material to be stable, but also can synergistically increase the catalytic activity of the whole composite material, and obviously improves the catalytic activity compared with the nickel-aluminum material not coated with the carbon membrane.
In some embodiments, the nanocomposite material of the present invention has a ratio of the content of carbon element determined by X-ray photoelectron spectroscopy to the content of carbon element determined by elemental analysis of not less than 10 in terms of mass ratio. As mentioned above, the carbon content determined by X-ray photoelectron spectroscopy refers to the relative carbon content on the surface of the material measured by quantitative element analysis using an X-ray photoelectron spectrometer as an analysis tool. The carbon element content determined in the element analysis refers to the relative content of the total carbon elements of the material, which is measured by carrying out element quantitative analysis by taking an element analyzer as an analysis tool. When the ratio of the carbon element determined by X-ray photoelectron spectroscopy to the carbon element determined by element analysis is larger, most of carbon in the whole nano composite material is concentrated on the surface of the material to form a carbon film layer, and further the nuclear film structure is formed.
In some embodiments, the raman spectrum of the nanocomposite material of the present invention is at 1580cm-1Intensity of nearby G peak at 1320cm-1The ratio of the intensities of the nearby D peaks is greater than 2. As will be understood by those skilled in the art, the peak D and the peak G are both Raman characteristic peaks of a crystal of C atoms, the peak D represents a defect in a lattice of carbon atoms, and the peak G represents a sp of C atoms2Hybrid in-plane stretching vibration. It is understood that a greater ratio of the intensity of the G peak to the intensity of the D peak indicates that more graphitic carbon is present in the nanocomposite than amorphous carbon. That is, the carbon element in the nanocomposite material of the present invention exists mainly in the form of graphitic carbon. The graphite carbon has better oxidation resistance, and can increase the catalytic activity with the core nano-particles in a synergistic manner, thereby improving the performance of the whole composite material.
In some embodiments, the aforementioned nuclear membrane structure generally has a particle size of 2nm to 100nm, preferably 5nm to 80 nm.
In some embodiments, the core of the nanocomposite of the present invention may further include an alkali metal oxide to enhance the performance of the material, depending on the requirements of the actual application. Wherein, the content of the alkali metal oxide accounts for no more than 5 percent of the content of the nano composite material by mass percent, and preferably no more than 2.5 percent.
The second aspect of the present invention provides a method for preparing the carbon-coated nickel-aluminum nanocomposite, comprising the following steps:
preparing a nickel-aluminum precursor; carrying out heating treatment on the nickel-aluminum precursor, and carrying out vapor deposition by taking low-carbon alkane as a carbon source gas; and carrying out oxygen treatment on the product after vapor deposition to obtain the carbon-coated nickel-aluminum nano composite material.
According to the preparation method provided by the invention, a nickel-aluminum precursor is prepared, and then the graphite shell is wrapped on the outer surface of the nickel-aluminum core in a vapor deposition mode. The nickel-aluminum precursor prepared by the invention generally has a hydrotalcite crystal structure, and can be prepared by various ways by those skilled in the art, such as coprecipitation and/or hydrothermal crystallization.
Specifically, the nickel aluminum precursor may be prepared by, but is not limited to, the following method.
According to a specific embodiment of the present invention, the nickel aluminum precursor is prepared by a coprecipitation method, and the specific steps may include: simultaneously dripping alkali liquor and aqueous solution containing trivalent aluminum salt and divalent nickel salt into water for precipitation treatment to enable trivalent aluminum salt and divalent nickel salt to generate coprecipitate; the coprecipitate is aged. The feeding amount of the aqueous solution containing the trivalent aluminum salt and the divalent nickel salt can be controlled according to the nickel-aluminum content in the target carbon-coated nickel-aluminum composite material, and the adding amount of the alkali liquor is controlled according to the condition that the trivalent aluminum salt and the divalent nickel salt are completely precipitated. The simultaneous addition of the alkali solution, the trivalent aluminum salt and the divalent nickel salt to the water can improve the dispersion effect of the alkali solution, the aluminum salt and the nickel salt during the initial dropwise addition. In addition, the trivalent aluminum salt and the divalent nickel salt are not particularly limited as long as they are soluble in water, and the alkali in the alkali solution is not particularly limited as long as they are capable of precipitating the trivalent aluminum salt and the divalent nickel salt, for example, the trivalent aluminum salt may include aluminum nitrate and/or aluminum chloride, the divalent nickel salt may include nickel nitrate and/or nickel chloride, and the molar ratio of aluminum in the trivalent aluminum salt to nickel in the divalent nickel salt may be 1: (2-4), the molar concentration of the trivalent aluminum salt can be 0.3-0.6 mol/L; the alkali liquor can be an aqueous solution containing sodium hydroxide and sodium carbonate, the concentration of the sodium hydroxide in the alkali liquor can be 0.2-4 mol/L, and the concentration of the sodium carbonate can be 0.1-2 mol/L; the ratio of the number of moles of sodium hydroxide to the total number of moles of aluminum and nickel in the trivalent aluminum salt and the divalent nickel salt may be (2-4): the ratio of the number of moles of the sodium carbonate to the total number of moles of aluminum and nickel in the trivalent aluminum salt and the divalent nickel salt can be (0.5-2): 1.
according to the invention, the precipitation treatment refers to a process of generating a precipitate from trivalent aluminum salt and divalent nickel salt by using an alkali solution, wherein the alkali solution can be mixed with the trivalent aluminum salt and the divalent nickel salt in various ways such as dripping, pumping or pouring. The aging treatment refers to further reacting the precipitate generated by the precipitation treatment to obtain the nickel-aluminum hydrotalcite crystal. The steps of the precipitation treatment and the aging treatment are not particularly limited, and only a nickel-aluminum precursor is obtained, for example, the conditions of the precipitation treatment may include: the temperature may be room temperature to less than 100 deg.c, preferably 40 deg.c to less than 100 deg.c, to increase the speed of the precipitation process. After the dropwise addition is started, the nickel ions and the aluminum ions are controlled to be precipitated under the condition that the pH value is greater than 7, preferably between 8 and 9, and the specific operation can be as follows: controlling the pH value of the aqueous solution to be between 8 and 9 through the dropping speed of the alkali liquor, accelerating the dropping speed of the alkali liquor if the pH value is lower than 8, and slowing down the dropping speed of the alkali liquor if the pH value is higher than 9; the aging treatment conditions may include: the temperature is 40 ℃ to less than 100 ℃, and the time is 2-72 hours, preferably 6-72 hours, and more preferably 24-48 hours. The nickel-aluminum hydrotalcite crystal obtained by aging treatment can be further washed to be neutral and dried to obtain a nickel-aluminum precursor.
In some embodiments, the temperature-rising heat treatment includes rising the temperature of the nickel-aluminum precursor to 500-900 ℃ in the presence of a protective gas, wherein the protective gas is nitrogen and/or argon, the flow rate of the protective gas is 10-500 ml/(min-g nickel-aluminum precursor), and the temperature-rising speed is 1-5 ℃/min. The protective gas is used as a carrier gas in the temperature rise process of the nickel-aluminum precursor, so that the danger of contact with air is avoided when the reduction and carbon deposition reaction of the nickel-aluminum precursor is carried out, and the graphite shell is prevented from being oxidized when contacting with air at high temperature after being coated with the graphite shell.
In some embodiments, the graphitic carbon shell is formed on the surface of the material by vapor deposition. The temperature of the vapor deposition is 750-900 ℃, preferably 780-850 ℃, and the time is 5-240 min, preferably 60-120 min; the carbon source gas is preferably methane or ethane, and the flow rate of the carbon source gas is 10-500 ml/(min g nickel-aluminum precursor), preferably 30-100 ml/(min g nickel-aluminum precursor), and more preferably 30-60 ml/(min g nickel-aluminum precursor).
According to the invention, after the nickel-aluminum precursor is obtained, the nickel-aluminum precursor after temperature-raising heat treatment is contacted with hydrogen to carry out reduction treatment. The reduction treatment has the functions of: on the one hand, the nickel-aluminum precursor existing in the form of hydroxide (hydrotalcite) is further dehydrated, and on the other hand, the generated nickel-aluminum oxide is reduced to generate simple substance nickel as an active center. The conditions of the hydrogen reduction treatment may include: the temperature is 500-900 ℃, the time is 120-480 minutes, and the hydrogen flow is 30-50 ml/(min. g nickel-aluminum precursor).
In some embodiments, the present invention further comprises mixing a nickel aluminum precursor with a salt solution of an alkali metal to perform a coprecipitation reaction, and subjecting the obtained precipitate to the aforementioned temperature-increasing heat treatment, wherein the molar ratio of the alkali metal to the nickel is not greater than 0.2. The inventors of the present invention have found that N is catalyzed when this material is used as a catalyst by the aforementioned coprecipitation reaction with a small amount of alkali metal before the temperature-raising heat treatment2When an acidic oxide such as O reacts, the catalytic activity is further improved.
In some embodiments, the invention further comprises subjecting the vapor deposited product to an oxygen treatment by which the material acquires a specific graphitized carbon film structure.
In some embodiments, the oxygen treatment comprises introducing standard gas into the pyrolyzed product and heating, wherein the standard gas comprises oxygen and balance gas, and the volume concentration of the oxygen is 10% to 40%, optionally 10% to 30%. The balance gas may be an inert gas such as nitrogen or argon, but the present invention is not limited thereto.
In some embodiments, the temperature of the oxygen treatment is from 200 ℃ to 500 ℃, preferably from 300 ℃ to 400 ℃; the time of the oxygen treatment is 0.5h to 10h, and then the carbon-coated nickel-aluminum nano composite material can be obtained.
As known to those skilled in the art, carbon is oxidized to generate gas after contacting with oxygen at high temperature, and it can be understood that the vapor-deposited product forms a nanocomposite material in which a graphitized carbon shell covers a nickel-aluminum core, wherein the carbon content is about 3% to 8%. After the product is treated with oxygen, most of the carbon in the material is lost with the oxidation reaction. However, the present inventors have unexpectedly found that the oxygen treated material, while burning off most of the carbon, not only oxidized the nickel and aluminum of the core, but also retained a small portion of the carbon. As mentioned above, XPS and Raman spectrum detection and analysis prove that the carbon is a graphitized carbon film layer coated on the surfaces of nickel oxide and aluminum oxide, and the carbon film layer further has a plurality of excellent properties, so that the nanocomposite has great application potential in catalytic materials, energy storage materials and electromagnetic materials.
The invention also provides the application of the nano composite material as a catalyst for decomposing nitrous oxide, which comprises the step of contacting the catalyst with the nitrous oxide to perform catalytic decomposition reaction to generate nitrogen and oxygen. Specifically, a gas containing dinitrogen monoxide is introduced into a reactor containing the catalyst to perform a catalytic decomposition reaction.
In some embodiments, the temperature of the catalytic decomposition reactionThe temperature is 300-400 ℃, preferably 350-380 ℃. The space velocity of the catalytic decomposition reaction is 1000h-1～3000h-1. The space velocity of the reaction is the amount of gas treated per unit volume of catalyst per unit time under the specified conditions, and is expressed in m3/(m3Catalyst h) can be simplified to h-1. The high reaction space velocity allowed by the invention shows that the catalyst has high activity and large device processing capacity when the reaction is applied.
According to the invention, as mentioned above, the currently reported decomposition N2The catalyst of O mainly comprises noble metal catalyst, ion-exchanged molecular sieve catalyst and transition metal oxide catalyst. Although the decomposition temperature of the noble metal catalyst is low, the expensive price of the noble metal catalyst is not suitable for large-scale industrial production; the high-efficiency decomposition temperature of other molecular sieve catalysts and transition metal oxide catalysts is 450-550 ℃, and the high temperature required by the reaction greatly improves the industrial cost; in addition, the decomposition of nitrous oxide generates oxygen, which tends to deactivate the catalyst.
The inventors of the present invention have found that the carbon-coated nickel-aluminum nanocomposite of the present invention can effectively decompose nitrous oxide into nitrogen and oxygen using as a catalyst, and exhibits excellent catalytic activity stability in the reaction. In addition, when the existing catalyst is used for catalyzing and decomposing the nitrous oxide, the high-concentration nitrous oxide obtained by industrial production generally needs to be diluted to be about 0.5-2 percent, and the catalyst can be directly decomposed to achieve a high decomposition rate without being diluted. Namely, the nitrous oxide can be subjected to catalytic decomposition reaction with the volume concentration of 30-40%, and the decomposition rate can reach more than 99%, so that the industrial cost is greatly reduced, and the method has a good industrial application prospect.
The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto. Unless otherwise specified, all reagents used in the invention are analytically pure.
The invention detects elements on the surface of the material by an X-ray photoelectron spectrum analyzer (XPS). The X-ray light usedThe electron energy spectrum analyzer is an ESCALb 220i-XL type ray electron energy spectrum analyzer which is manufactured by VG scientific company and is provided with Avantage V5.926 software, and the test conditions of X-ray photoelectron spectrum analysis are as follows: the excitation source is monochromatized A1K alpha X-ray, the power is 330W, and the basic vacuum is 3X 10 during analysis and test-9mbar。
The analysis of carbon (C) element is carried out on an Elementar Micro Cube element analyzer which is mainly used for analyzing four elements of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N), and the specific operation method and conditions are as follows: weighing 1-2 mg of a sample in a tin cup, placing the sample in an automatic sample feeding disc, feeding the sample into a combustion tube through a ball valve for combustion, wherein the combustion temperature is 1000 ℃ (the atmosphere interference during sample feeding is removed, helium is adopted for blowing), and then reducing the combusted gas by using reduced copper to form nitrogen, carbon dioxide and water. The mixed gas is separated by three desorption columns and sequentially enters a TCD detector for detection. The oxygen element is analyzed by converting oxygen in a sample into CO under the action of a carbon catalyst by utilizing pyrolysis, and then detecting the CO by adopting TCD. Since the composite material of the present invention contains only carbon and a metal oxide, the total content of the metal oxide can be determined from the content of the carbon element.
The ratio between the different metal oxides was measured by an X-ray fluorescence spectrometer (XRF), and the content of the different metal oxides in the composite material was calculated from the known content of carbon element. The X-ray fluorescence spectrum analyzer (XRF) adopted by the invention is a Rigaku 3013X-ray fluorescence spectrometer, and the X-ray fluorescence spectrum analysis and test conditions are as follows: the scanning time was 100s and the atmosphere was air.
The Raman detection adopts a LabRAM HRUV-NIR laser confocal Raman spectrometer produced by HORIBA company of Japan, and the laser wavelength is 325 nm.
The high-resolution transmission electron microscope (HRTEM) adopted by the invention is JEM-2100(HRTEM) (Nippon electronics Co., Ltd.), and the test conditions of the high-resolution transmission electron microscope are as follows: the acceleration voltage was 200 kV.
The model of the XRD diffractometer adopted by the invention is an XRD-6000X-ray powder diffractometer (Shimadzu Japan), and the XRD test conditions are as follows: the Cu target was irradiated with K α rays (wavelength λ is 0.154nm), tube voltage was 40kV, tube current was 200mA, and scanning speed was 10 ° (2 θ)/min.
Example 1
This example illustrates the preparation of a carbon-coated nickel aluminum nanocomposite material according to the invention.
(1) Weighing 11.64g (0.04mol) of nickel nitrate hexahydrate and 7.5g (0.02mol) of aluminum nitrate nonahydrate, adding 60ml of deionized water to prepare a mixed salt solution, preparing a mixed alkali solution by adding 5.40g (0.135mol) of sodium hydroxide, 5.08g (0.048mol) of anhydrous sodium carbonate and 120ml of deionized water, simultaneously dripping the two mixed solutions into a 100ml of deionized water three-neck flask which is pre-filled with constant temperature of 60 ℃, stirring simultaneously, strictly controlling the pH value of the precipitate of the trivalent aluminum salt and the divalent nickel salt in the three-neck flask to be 8.4 (namely controlling the pH value to be 8.3-8.5), continuously stirring at 60 ℃ for 30min after finishing dripping, aging at 80 ℃ for 24h, centrifuging and washing to be neutral, drying at 80 deg.C for 4 hr, mixing with 0.14g (0.001mol) potassium carbonate, adding 150ml deionized water, stirring at 60 deg.C for 10 hr, and drying at 80 deg.C for 10 hr to obtain nickel-aluminum precursor coprecipitated with alkali metal.
(2) Weighing 1.0g of the nickel-aluminum precursor obtained in the step (1), placing the nickel-aluminum precursor into a porcelain boat, then placing the porcelain boat into a tubular furnace in a nitrogen protective atmosphere, carrying out programmed temperature rise of 5 ℃/min at the nitrogen flow of 100mL/min, raising the temperature to 500 ℃, introducing 30mL/min of hydrogen for 180min, and closing the hydrogen; and continuously raising the temperature to 800 ℃, introducing 50mL/min of methane at the temperature, reacting for 60min, closing the methane after the reaction is finished, and naturally cooling in a nitrogen atmosphere to obtain the composite material coated with the carbon shell after vapor deposition.
(3) And (3) placing the material obtained in the step (2) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing standard gas (15% of oxygen and balance gas) with the flow rate of 100mL/min, heating to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 8 hours, stopping heating, and cooling to room temperature under the atmosphere of the standard gas to obtain black solid, namely the nano composite material.
Material characterization:
fig. 1 is an X-ray diffraction pattern (XRD) of the nanocomposite material of example 1, and it can be seen from fig. 1 that nickel in the nanocomposite material exists as an oxide after mild oxidation treatment, and fig. 2a and 2b respectively show Transmission Electron Micrographs (TEM) of the nanocomposite material of example 1 at different magnifications, and it can be observed that the material surface has a carbon layer thin film and the particle diameter is about 5 to 20 nm.
As can be seen from X-ray fluorescence spectrum analysis (XRF) and elemental analysis, the nanocomposite had a carbon content of 0.79 wt%, a nickel oxide content of 77.14 wt%, an aluminum oxide content of 20.05 wt%, and a potassium oxide content of 2.02 wt%. It was found by X-ray photoelectron spectroscopy (XPS) analysis that carbon, oxygen, nickel, aluminum, and potassium were detected as surface layer elements of the nanocomposite. Wherein the ratio of the carbon element content of the surface layer to the total carbon element content is 32.7/1. It can be seen that the carbon in the nanocomposite is mainly present on the surface of the core film structure. FIG. 3 shows a Raman spectrum of the nanocomposite, wherein the G peak (1580 cm)-1) Intensity of (3) and intensity of D peak (1320 cm)-1) The ratio of (A) to (B) is 2.1/1. It can be seen that most of the carbon in this material is graphitic carbon.
Example 2
This example illustrates the preparation of a carbon-coated nickel aluminum nanocomposite material according to the invention.
(1) Weighing 11.64g (0.04mol) of nickel nitrate hexahydrate and 7.5g (0.02mol) of aluminum nitrate nonahydrate, adding 60ml of deionized water to prepare a mixed salt solution, adding 5.40g (0.135mol) of sodium hydroxide and 5.08g (0.048mol) of anhydrous sodium carbonate and 120ml of deionized water to prepare a mixed alkali solution, simultaneously dropwise adding the two mixed solutions into a 100ml of deionized water pre-filled with constant temperature of 60 ℃, stirring simultaneously, strictly controlling the pH value of the precipitate of trivalent aluminum salt and divalent nickel salt in the three-neck flask to be 8 (namely controlling the precipitate to be 7.9-8.1), continuously stirring at 60 ℃ for 30min after dropwise adding, aging at 80 ℃ for 24h, centrifugally washing to be neutral, and drying at 80 ℃ to obtain the nickel-aluminum precursor.
(2) Weighing 1.0g of the nickel-aluminum precursor obtained in the step (1), placing the nickel-aluminum precursor into a porcelain boat, then placing the porcelain boat into a tubular furnace in a nitrogen protective atmosphere, carrying out programmed temperature rise of 5 ℃/min at the nitrogen flow of 100mL/min, raising the temperature to 500 ℃, introducing 30mL/min of hydrogen for 240min, and closing the hydrogen; and continuously raising the temperature to 800 ℃, introducing 50mL/min of methane at the temperature, reacting for 60min, closing the methane after the reaction is finished, and naturally cooling in a nitrogen atmosphere to obtain the composite material coated with the carbon shell after vapor deposition.
(3) And (3) placing the material obtained in the step (2) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing standard gas (15% of oxygen and balance gas) with the flow rate of 100mL/min, heating to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 10 hours, stopping heating, and cooling to room temperature under the atmosphere of the standard gas to obtain black solid, namely the nano composite material.
Material characterization:
fig. 4 is an X-ray diffraction pattern (XRD) of the nanocomposite material of example 2, and as can be seen from fig. 4, after mild oxidation treatment, nickel in the nanocomposite material exists as an oxide, and fig. 5a and 5b show Transmission Electron Micrographs (TEM) of the nanocomposite material of example 2 at different magnifications, respectively, and it can be observed that the surface of the material has a carbon layer thin film and the particle size is about 5 to 20 nm.
As can be seen from X-ray fluorescence spectrum analysis (XRF) and elemental analysis, the nanocomposite had a carbon content of 0.95 wt%, a nickel oxide content of 77.14 wt%, and an aluminum oxide content of 21.64 wt%. It was found by X-ray photoelectron spectroscopy (XPS) analysis that carbon, oxygen, nickel, and aluminum were detected as surface layer elements of the nanocomposite. Wherein the ratio of the carbon element content of the surface layer to the total carbon element content is 43/1. It can be seen that the carbon in the nanocomposite is mainly present on the surface of the core film structure. FIG. 6 shows a Raman spectrum of the nanocomposite, wherein the G peak (1580 cm)-1) Intensity of (3) and intensity of D peak (1320 cm)-1) The ratio of (A) to (B) is 2.4/1. It can be seen that most of the carbon in this material is graphitic carbon.
Comparative example 1
Placing the nickel-aluminum precursor obtained in the step (1) in the embodiment 1 in a porcelain boat, then placing the porcelain boat in a tubular furnace in a nitrogen protective atmosphere, carrying out programmed temperature rise of 5 ℃/min at a nitrogen flow of 100mL/min, raising the temperature to 500 ℃, introducing 30mL/min hydrogen for 180min, closing the hydrogen, and naturally cooling in a hydrogen atmosphere to obtain an intermediate product.
And then placing the intermediate product in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing standard gas (15% of oxygen and balance gas) with the flow rate of 100mL/min, heating to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 3h, stopping heating, and cooling to room temperature under the atmosphere of the standard gas to obtain the nickel-aluminum composite oxide without carbon film coating.
As can be seen from X-ray fluorescence spectrum analysis (XRF) and elemental analysis, the material contained 76.94 wt% of nickel oxide, 20.87 wt% of aluminum oxide, and 2.19 wt% of potassium oxide.
Comparative example 2
Placing the nickel-aluminum precursor obtained in the step (1) in the embodiment 2 in a porcelain boat, then placing the porcelain boat in a tubular furnace in a nitrogen protection atmosphere, carrying out programmed temperature rise at 5 ℃/min under the nitrogen flow of 100mL/min, heating to 500 ℃, introducing 30mL/min hydrogen for 240min, closing the hydrogen, and naturally cooling under the hydrogen atmosphere to obtain an intermediate product.
And then placing the intermediate product in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing standard gas (15% of oxygen and balance gas) with the flow rate of 100mL/min, heating to 350 ℃ at the speed of 2 ℃/min, keeping the temperature for 3h, stopping heating, and cooling to room temperature under the atmosphere of the standard gas to obtain the nickel-aluminum composite oxide without carbon film coating.
As can be seen from X-ray fluorescence spectrum analysis (XRF) and elemental analysis, the nickel oxide content in this material was 77.96 wt%, and the aluminum oxide content was 22.04 wt%.
Application example 1
This application example serves to illustrate the reaction of catalyzing the decomposition of nitrous oxide using the nanocomposite of example 1 as a catalyst.
0.5g of catalyst was placed in a continuous flow fixed bed reactor with the reaction gas consisting of 38.0% by volume N2O, using nitrogen as balance gas, the flow rate of the reaction gas is 15ml/min, and the space velocity is 1800h-1The activity evaluation temperature range was 300The catalyst is used for catalyzing and decomposing N at the temperature of between 500 and DEG C2The conversion of O is shown in Table 1.
Application example 2
N Using the method of application example 12O decomposition reaction, except that the nanocomposite of example 2 was used as a catalyst, the results are shown in table 1.
Comparative application example 1
N Using the method of application example 12O decomposition reaction, except that the material of comparative example 1 was used as a catalyst, the results are shown in table 1.
Comparative application example 2
N Using the method of application example 12O decomposition reaction, except that the material of comparative example 2 was used as the catalyst, the results are shown in table 1.
TABLE 1
Figure BDA0002241489200000141
As can be seen from Table 1 above, the carbon-coated nickel-aluminum nanocomposite prepared by the method of the present invention is superior to uncoated pure nickel-aluminum oxide in the case of N2O has better catalytic decomposition performance, and N can be decomposed with high efficiency in a relatively low temperature range2O, whereas the materials of comparative examples 1 and 2 require temperatures of at least 430 ℃ or 465 ℃ to be able to convert N2The conversion rate of O reaches more than 99 percent, and the decomposition can be relatively complete. In addition, the composite material contains a certain content of alkali metal oxide, so that the catalytic performance is improved to a certain extent.
It can be seen that the nanocomposite material of the invention has good catalytic effect on the decomposition of nitrous oxide, and can efficiently decompose and eliminate N at a lower temperature2O, application thereof to industrial process waste gas N2In the treatment of O, e.g. high concentrations of N produced during the production in adipic acid plants and nitric acid plants2The elimination of O waste gas can greatly reduce the reaction temperature and the energy consumption, and has good industrial application prospect.
It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.

Claims (21)

1. A carbon-coated nickel-aluminum nanocomposite material is characterized by comprising a core film structure with an outer film and an inner core, wherein the outer film is a graphitized carbon film, and the inner core comprises nickel oxide and aluminum oxide, wherein the nickel oxide content is 59% -80%, the aluminum oxide content is 19% -40%, and the carbon content is not more than 1% based on the total mass of the nanocomposite material.
2. The nanocomposite as claimed in claim 1, wherein the nickel oxide content is 69 to 79%, the aluminum oxide content is 20 to 30%, and the carbon content is 0.3 to 1%.
3. Nanocomposite material according to claim 1, characterized in that the nanocomposite material has a content of carbon element determined by X-ray photoelectron spectroscopy to carbon element determined by elemental analysis of not less than 10 in terms of mass ratio.
4. Nanocomposite material according to claim 1, wherein the raman spectrum of the nanocomposite material is at 1580cm-1Intensity of nearby G peak at 1320cm-1The ratio of the intensities of the nearby D peaks is greater than 2.
5. The nanocomposite as claimed in claim 1, wherein the core-film structure has a particle size of 2nm to 100 nm.
6. Nanocomposite material according to claim 1, wherein the core further comprises an alkali metal oxide, the content of which in mass percent does not exceed 5%, preferably 2.5%, of the content of the nanocomposite material.
7. A method for preparing the carbon-coated nickel-aluminum nanocomposite material according to any one of claims 1 to 6, comprising the steps of:
preparing a nickel-aluminum precursor;
carrying out heating treatment on the nickel-aluminum precursor, and carrying out vapor deposition by taking low-carbon alkane as a carbon source gas;
and carrying out oxygen treatment on the product after vapor deposition to obtain the nano composite material.
8. The preparation method according to claim 7, wherein the oxygen treatment comprises introducing a standard gas into the vapor-deposited product and heating, wherein the standard gas comprises oxygen and a balance gas, and the volume concentration of the oxygen is 10-40%.
9. The method according to claim 7, wherein the temperature of the oxygen treatment is 200 to 500 ℃ and the time of the oxygen treatment is 0.5 to 10 hours.
10. The preparation method according to claim 7, wherein the manner of preparing the nickel aluminum precursor is coprecipitation and/or hydrothermal crystallization.
11. The method according to claim 7, wherein the step of preparing a nickel-aluminum precursor comprises:
simultaneously dripping alkali liquor and aqueous solution containing trivalent aluminum salt and divalent nickel salt into water for precipitation treatment to enable trivalent aluminum salt and divalent nickel salt to generate coprecipitate;
and aging the coprecipitate.
12. The method according to claim 11, wherein the trivalent aluminum salt comprises aluminum nitrate and/or aluminum chloride, the divalent nickel salt comprises nickel nitrate and/or nickel chloride, and a molar ratio of aluminum in the trivalent aluminum salt to nickel in the divalent nickel salt is 1: (2-4); the alkali liquor is an aqueous solution containing sodium hydroxide and sodium carbonate, the concentration of the sodium hydroxide in the alkali liquor is 0.2-4 mol/L, and the concentration of the sodium carbonate is 0.1-2 mol/L; the ratio of the mole number of the sodium hydroxide to the total mole number of the aluminum and the nickel in the trivalent aluminum salt and the divalent nickel salt is (2-4): 1, the ratio of the mole number of the sodium carbonate to the total mole number of the aluminum and the nickel in the trivalent aluminum salt and the divalent nickel salt is (0.5-2): 1.
13. the method according to claim 11, wherein the precipitation treatment is carried out at a temperature of 40 ℃ to less than 100 ℃, the aging treatment is carried out at a temperature of 40 ℃ to less than 100 ℃, and the aging treatment is carried out for 2 to 48 hours.
14. The preparation method according to claim 7, further comprising contacting the nickel-aluminum precursor subjected to the temperature-raising heat treatment with hydrogen to perform reduction treatment, wherein the temperature of the reduction treatment is 500-900 ℃, the time is 120-480 min, and the hydrogen flow rate is 30-50 ml/(min-g nickel-aluminum precursor).
15. The preparation method according to claim 7, further comprising mixing the nickel aluminum precursor with a salt solution of an alkali metal to perform a coprecipitation reaction, and then subjecting the obtained precipitate to the temperature-increasing heat treatment, wherein the molar ratio of the alkali metal to nickel is not more than 0.2.
16. The preparation method according to claim 7, wherein the temperature-raising heat treatment comprises raising the temperature of the nickel-aluminum precursor to 500-900 ℃ in the presence of a protective gas, wherein the protective gas is nitrogen and/or argon, the flow rate of the protective gas is 10-500 ml/(min-g nickel-aluminum precursor), and the temperature-raising speed is 1-5 ℃/min; the vapor deposition temperature is 750-900 ℃, and the time is 5-240 minutes; the carbon source gas is methane or ethane, and the flow rate of the carbon source gas is 10-500 ml/(min. g nickel-aluminum precursor).
17. Use of a nanocomposite according to any one of claims 1 to 6 as a catalytic material, an energy storage material or an electromagnetic material.
18. Use of a nanocomposite according to any one of claims 1 to 6 as a catalyst for decomposing nitrous oxide, comprising: and contacting the catalyst with nitrous oxide to perform a catalytic decomposition reaction to generate nitrogen and oxygen.
19. Use according to claim 18, wherein the temperature of the catalytic decomposition reaction is between 300 ℃ and 400 ℃.
20. Use according to claim 18, wherein the catalytic decomposition reaction has a space velocity of 1000h-1～3000h-1。
21. Use according to claim 18, wherein the nitrous oxide is present in a concentration of between 30% and 40% by volume.
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