Carbon-coated nickel oxide nanocomposite, its manufacturing method and application

Abstract

A carbon-coated nickel oxide nanocomposite, its manufacturing method, and applications are disclosed. The nanocomposite contains carbon-coated nickel oxide nanoparticles having a core-shell structure. The core-shell structure includes an outer shell that is a graphitized carbon film (optionally doped with nitrogen) and an inner core that contains nickel oxide nanoparticles. The carbon content of the nanocomposite is greater than 0 wt. % and less than or equal to about 5 wt. % based on the weight of the nanocomposite. The nanocomposite exhibits excellent catalytic activity and can be effectively used to catalyze a variety of reactions, making it particularly promising for industrial applications.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 201911001538.3 ("Carbon-Coated Nickel Oxide Nanocomposite Material, Its Manufacturing Method and Application", filed October 21, 2019), Chinese Patent Application No. 201911002419.X ("Method for Catalytic Combustion of Volatile Organic Compounds", filed October 21, 2019), Chinese Patent Application No. 202010503595.8 ("Carbon-Coated Nickel Oxide Nanocomposite Material, Its Manufacturing Method and Application", filed June 5, 2020), and Chinese Patent Application No. 202010503588.8 ("Method for Catalytic Combustion of Volatile Organic Compounds", filed June 5, 2020), the contents of which are incorporated herein by reference in their entireties.

[0002] [Technical Field] This application relates to the field of catalyst technology. In particular, this application relates to carbon-coated nickel oxide nanocomposites and their manufacturing methods and applications. [Background technology]

[0003] Transition metal oxides have excellent catalytic and electromagnetic properties. Therefore, they have been the subject of active research in the field of inorganic materials and have found wide applications in energy storage, catalytic, magnetic recording, and biomedicine. Carbon materials have excellent electrical conductivity, excellent chemical and electrochemical stability, and high structural strength. Coating active metal or metal oxide nanoparticles with carbon materials effectively improves the conductivity and stability of nanomaterials. Furthermore, the carbon coating has a encapsulating effect on nanoparticles, making them less likely to aggregate. In recent years, carbon-coated nanomaterials have been widely used in fields such as electrocatalysis, supercapacitor materials, anode materials for lithium-ion batteries, and biotechnology. However, their use in catalysis has been limited.

[0004] Nitrous oxide (N2O), known as laughing gas, is a significant greenhouse gas. The global warming potential (GWP) of N2O is 310 times that of CO2 and 21 times that of CH4. Furthermore, N2O persists in the atmosphere for an average of about 150 years and is also a major source of NOx in the stratosphere. N2O not only severely damages the ozone layer but also has a strong greenhouse effect.

[0005] Adipic acid production in China primarily relies on the cyclohexanol-nitric acid oxidation process. This process involves oxidizing cyclohexanol with nitric acid to produce adipic acid. This is a mature technology, producing a high-yield, high-purity product. However, this process requires a large amount of nitric acid, generates a large amount of NO during the reaction, and the tail gas emitted during the production process is concentrated to a high volume and high concentration (36-40%). Currently, 150,000 tons of adipic acid are produced annually using the cyclohexanol-nitric acid oxidation process, and annual NO emissions can reach 45,000 tons. Therefore, the purification of tail gas generated by adipic acid plants and the effective control and reduction of NO have become the focus of research in the field of environmental catalysis.

[0006] Direct catalytic cracking can decompose N2O into nitrogen and oxygen. This is the most effective and clean technology for removing N2O. Catalysts are the core of direct catalytic cracking. Currently developed and reported catalysts for N2O decomposition mainly include noble metal catalysts, ion-exchange molecular sieve catalysts, and transition metal oxide catalysts. Noble metal catalysts (e.g., Rh, Ru) have high catalytic activity at low temperatures for N2O decomposition (effectively decomposing N2O at temperatures between 250 and 350°C). However, the high cost of noble metal catalysts limits their large-scale application. Molecular sieve catalysts and transition metal oxide catalysts are much cheaper than noble metal catalysts. However, these two currently available catalysts have relatively low catalytic activity for N2O decomposition, with efficient decomposition temperatures limited to 450–550°C. Furthermore, high-concentration nitrous oxide gas must be diluted to approximately 0.5–2% for decomposition, significantly increasing industrial costs.

[0007] Volatile organic compounds (VOCs) are organic compounds with a saturated vapor pressure of more than 70 Pa at room temperature and a boiling point of less than 260°C at atmospheric pressure. VOCs come in a wide variety of forms, primarily alkanes, aromatic compounds, esters, aldehydes, and halogenated hydrocarbons. Many VOCs have a pungent odor and are toxic and carcinogenic. VOCs are also a major cause of photochemical smog and PM2.5 (particulate matter) in the atmosphere. China, a major manufacturing nation, is the world's largest emitter of VOCs. Furthermore, VOCs emitted by industrial production are highly concentrated, long-lasting, and contain a variety of pollutants, posing a serious threat to human health and causing serious damage to the ecological environment. In recent years, China has systematically implemented measures to prevent and treat VOC pollutants. The development of efficient VOC purification technologies and the reduction of VOC emissions have become key challenges in the field of environmental protection.

[0008] There are two methods for purifying VOCs. The first is physical absorption and adsorption, which is effective at high concentrations (5000 mg / m 3 However, physical absorption and adsorption methods are generally used to recover VOCs at low concentrations (1000 mg / m 3 The second method is the chemical reaction method, which converts VOCs into non-toxic chemicals by introducing an oxidizing agent to oxidize them. The chemical reaction method is primarily used to treat medium or low concentrations of VOCs.

[0009] Among chemical reaction methods, combustion technology is widely used. Combustion technology can be further classified into direct flame combustion and catalytic combustion. Direct flame combustion is a method in which VOCs are burned directly as fuel. Direct flame combustion requires high temperatures of 600-900°C, which requires a large amount of energy and can produce black smoke and unpleasant odors due to incomplete combustion. Catalytic combustion is a typical gas-solid catalytic reaction that catalyzes the reaction of VOCs adsorbed on a catalytic surface with O2, converting them into harmless CO2 and H2O. Catalytic combustion is usually carried out at temperatures of 300-500°C, which reduces energy consumption and does not generate secondary pollution. Therefore, catalytic combustion is an energy-saving, effective, economical, and environmentally friendly technology.

[0010] Catalysts are at the core of catalytic combustion technology. Currently developed and known catalysts for catalytically decomposing and burning VOCs mainly include precious metal catalysts and non-precious metal oxide catalysts. Of these, precious metal catalysts (Pt, Ru, Au, Pd, etc.) have good performance but are expensive and prone to poisoning. Non-precious metal oxide catalysts (Co2O3, MnO2, CeO2, CuO, TiO2, perovskite, etc.) are inexpensive and less prone to poisoning but have relatively low catalytic activity.

[0011] Therefore, the development of inexpensive, high-performance catalysts that can be applied to the above-mentioned fields has become a problem to be solved.

[0012] The information in the Background section is provided solely to aid in understanding the background of the present application, and therefore, please note that it may contain information that does not constitute prior art already known to those skilled in the art. Summary of the Invention

[0013] The purpose of this application is to provide a carbon-coated nickel oxide nanocomposite material with a core-shell structure, as well as its manufacturing method and applications. The core-shell structure comprises a shell of graphitized carbon (optionally doped with nitrogen) and a core of nickel oxide. Carbon-coated nickel oxide nanoparticles have excellent activity when used as a catalytically active component. The nanocomposite material can be effectively used in the catalytic decomposition of nitrous oxide and the catalytic combustion of volatile organic compounds. The nanocomposite material solves problems such as the removal of high concentrations of NO generated in manufacturing processes such as adipic acid plants and nitric acid plants, and the purification of VOCs. Therefore, nanocomposites are of great significance for environmental protection and the reduction of air pollution, and are expected to be used in industry.

[0014] To achieve the above object, the present application provides, in one embodiment, a carbon-coated nickel oxide nanocomposite material comprising carbon-coated nickel oxide nanoparticles having a core-shell structure, The core-shell structure has an outer shell that is a graphitized carbon film (optionally doped with nitrogen) and an inner core that contains nickel oxide nanoparticles; The nanocomposite has a carbon content of greater than 0% to about 5% by weight, based on the weight of the nanocomposite.

[0015] Preferably, the nanocomposite material satisfies the following (i) and / or (ii): (i) The carbon element content measured by X-ray photoelectron spectroscopy is about 15–60 mol%; (ii) the ratio of the elemental carbon mass content as determined by X-ray photoelectron spectroscopy to the elemental carbon mass content as determined by elemental analysis is greater than or equal to about 10;

[0016] Preferably, in the Raman spectrum of the nanocomposite material, -1 The intensity of the G peak located near 1320 cm -1 The ratio of the intensity of the D peak to that of the nearby D peak is greater than about 2.

[0017] In another aspect, the present application provides a method for producing a carbon-coated nickel oxide nanocomposite, comprising the steps of: (i) mixing a nickel source, a polybasic organic carboxylic acid, and an optional nitrogen-containing compound in a solvent to form a homogeneous solution; (ii) removing the solvent from the homogeneous solution to obtain a precursor; (iii) pyrolyzing the precursor under an inert or reducing atmosphere; (iv) heat treating the pyrolysis product in the presence of oxygen to obtain a nanocomposite; where: Preferably, the nickel source is one or more selected from the group consisting of nickel powder, nickel hydroxide, nickel oxide, a soluble organic acid salt of nickel, a basic carbonate of nickel, and a carbonate of nickel; Preferably, the polybasic organic carboxylic acid is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, malic acid, ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propanediaminetetraacetic acid; Preferably, the nitrogen-containing compound is one or more selected from the group consisting of urea, melamine, dicyanodiamine, hexamethylenetetramine, and amino acids.

[0018] Preferably, the heat treatment in step (iv) includes a step of introducing an oxygen-containing gas into the pyrolysis product and heating the pyrolysis product; The oxygen concentration of the oxygen-containing gas is about 10 to 40% by volume, The temperature of the heat treatment is about 200 to 500°C. The heat treatment time is about 0.5 to 10 hours.

[0019] In a further aspect, the present application provides a method for catalyzing the decomposition of nitrous oxide, comprising contacting nitrous oxide and a catalytic cracking catalyst to produce nitrogen and oxygen; The catalyst comprises the nanocomposite material of the present application as the active component.

[0020] In yet another aspect, the present application provides a method for treating volatile organic compounds, comprising contacting the volatile organic compounds with a catalyst for an oxidation reaction, The catalyst comprises the nanocomposite material of the present application as the active component.

[0021] Preferably, the mixed gas containing the volatile organic compounds and oxygen is brought into contact with a catalytic combustion catalyst to cause an oxidation reaction.

[0022] The carbon-coated nickel oxide nanocomposite of the present application has a core-shell structure comprising a shell of graphitized carbon (optionally doped with nitrogen) and a core of nickel oxide. Due to its unique structure and composition, it exhibits excellent activity when used as a catalyst for the decomposition of NO. While conventional catalysts require dilution of NO contained in industrial waste gases before treatment, the nanocomposite of the present application can directly catalyze the decomposition of waste gases containing high concentrations of nitrous oxide generated by industrial production at low temperatures with a decomposition efficiency of over 99%. This has great significance for environmental protection and air pollution reduction. Furthermore, the nanocomposite can also effectively catalyze the oxidation and combustion of VOCs at low temperatures. This is beneficial for solving problems related to VOC purification and air pollution reduction.

[0023] The drawings that form part of this specification are provided to aid in the understanding of this application, The present application can be read with reference to the following drawings in combination with the detailed description below. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 shows the X-ray diffraction pattern of the nanocomposite material obtained in Example I-1. [Figure 2] FIG. 2 shows a transmission electron microscope image of the nanocomposite material obtained in Example I-1. [Figure 3]FIG. 3 shows the Raman spectrum of the nanocomposite material obtained in Example I-1. [Figure 4] FIG. 4 shows the X-ray diffraction pattern of the nanocomposite material obtained in Example I-2. [Figure 5] FIG. 5 shows a transmission electron microscope image of the nanocomposite material obtained in Example I-2. [Figure 6] FIG. 6 shows the Raman spectrum of the nanocomposite material obtained in Example I-2. [Figure 7] FIG. 7 shows the X-ray diffraction pattern of the material obtained in Comparative Example I-1. [Figure 8a] 8a and 8b show TEM images of the material obtained in Comparative Example I-1 at different magnifications. [Figure 8b] See column Figure 8a. [Figure 9] FIG. 9 shows the X-ray diffraction pattern of the nanocomposite material obtained in Example II-1. [Figure 10] FIG. 10 shows a transmission electron microscope image of the nanocomposite material obtained in Example II-1. [Figure 11] FIG. 11 shows the Raman spectrum of the nanocomposite material obtained in Example II-1. [Figure 12] FIG. 12 shows the X-ray diffraction pattern of the nanocomposite material obtained in Example II-2. [Figure 13] FIG. 13 shows a TEM image of the nanocomposite material obtained in Example II-2. [Figure 14] FIG. 14 shows the Raman spectrum of the nanocomposite material obtained in Example II-2. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following various embodiments or examples are provided to enable those skilled in the art to practice the present invention by referring to the description herein. Of course, these embodiments or examples are merely illustrative and are not intended to limit the present application. Any specific numerical value described herein, including the endpoints of a range, is not limited to that exact value. Instead, the specific numerical value should be construed to include all values ​​close to that exact value. Furthermore, with respect to any numerical range described herein, the endpoints of the range, the endpoints of the range and any specific value within the range, and any specific value within the range can be combined in any way to create one or more new numerical ranges. Such new numerical ranges should also be considered to be specifically described in the present application.

[0026] Unless otherwise specified, terms used herein have the same meaning as commonly understood by those skilled in the art. When a term is defined herein and its definition differs from that commonly understood in the art, the definition herein shall prevail.

[0027] All patent and non-patent literature (including, but not limited to, textbooks and journal articles) cited herein is incorporated by reference in its entirety.

[0028] As used herein, the term "core-shell structure" refers to a core-shell structure having an outer graphitic carbon shell and an inner core containing nickel oxide nanoparticles. The composite particles formed by coating nickel oxide nanoparticles with a graphitic carbon shell are spherical or nearly spherical.

[0029] The term "graphitized carbon shell / film" refers to a thin film structure that is primarily composed of graphitized carbon.

[0030] The term "nitrogen" when appearing in the expressions "nitrogen-doped" or "doped with nitrogen" refers to elemental nitrogen. Specifically, it refers to elemental nitrogen present in various forms in the graphitized carbon layer formed in the production of the carbon-coated nickel oxide nanocomposite. The term "nitrogen content" refers to the total content of all forms of elemental nitrogen.

[0031] The term "carbon elemental content as measured by X-ray photoelectron spectroscopy" refers to the relative content of carbon element at the surface of a material as determined by quantitative elemental analysis using an X-ray photoelectron spectroscopy as the analytical instrument. This parameter is usually expressed in mol%, and a simple conversion allows the calculation of the corresponding mass %.

[0032] The term "nitrogen element content as measured by X-ray photoelectron spectroscopy" refers to the relative content of nitrogen element at the surface of a material as determined by quantitative elemental analysis using an X-ray photoelectron spectroscopy as the analytical instrument. This parameter is usually expressed in mol%.

[0033] The term "carbon elemental content as determined by elemental analysis" refers to the relative content of the total carbon element in a material as determined by quantitative elemental analysis using an elemental analyzer as the analytical instrument. This parameter is usually expressed as % by weight.

[0034] For the purposes of this application, the reaction space velocity refers to the amount of gas processed per unit time and per unit mass of catalyst under given conditions. This parameter is expressed as: volume of reacted gas (mL) / (hr · weight of catalyst (g)).

[0035] As mentioned above, in a first aspect, the present application provides a carbon-coated nickel oxide nanocomposite material comprising carbon-coated nickel oxide nanoparticles having a core-shell structure, the core-shell structure comprises an outer shell that is a graphitized carbon film (optionally doped with nitrogen) and an inner core that contains nickel oxide nanoparticles; The carbon content of the nanocomposite is greater than 0% and less than or equal to about 5% by weight, based on the weight of the nanocomposite.

[0036] In a preferred embodiment, the nanocomposite consists essentially of carbon-coated nickel oxide nanoparticles having a core-shell structure.

[0037] In a preferred embodiment, the inner core consists essentially of nickel oxide nanoparticles.

[0038] According to the present application, the carbon content of a nanocomposite material by weight may be the carbon element content measured by elemental analysis. In a preferred embodiment, the carbon content of the nanocomposite material is about 1 wt% or less (e.g., about 0.1 to 1 wt%), preferably less than about 1 wt% (e.g., about 0.1 to 0.99 wt%, about 0.1 to 0.95 wt%, 0.2 to 0.95 wt%, 0.3 to 0.95 wt%, 0.4 to 0.95 wt%, 0.5 to 0.95 wt%, 0.5 to 0.9 wt%, etc.), more preferably about 0.2 to 0.95 wt%, and particularly preferably about 0.4 to 0.95 wt%.

[0039] According to the present application, the carbon-coated nickel oxide nanocomposite material has a core-shell structure with an outer shell layer and an inner core layer. The outer shell layer is mainly composed of a graphitized carbon film, optionally doped with nitrogen. The graphitized carbon film has a thin film structure, which is mainly composed of graphitized carbon, optionally doped with nitrogen. The graphitized carbon film coats the surface of the nickel oxide nanoparticles. The present inventors have surprisingly found that a core-shell structure whose outer surface is coated with a graphitized carbon film significantly improves the performance (especially catalytic activity) of the entire material, despite the relatively low carbon content of the shell layer. Without being bound by any theory, the applicant believes that the graphitized carbon film of the nanocomposite material according to the present application has a confining effect, effectively preventing the aggregation and growth of nickel oxide nanoparticles in the core. This stabilizes the catalytic activity of the composite material and synergistically increases the catalytic activity of the entire composite material. As a result, the catalytic activity of the composite material is significantly improved compared to pure nickel oxide without a graphitic carbon film coating. In addition, nitrogen doping can change the elemental composition of the carbon material, allowing for tuning and control of the electrochemical properties and surface activity of the carbon material. Therefore, nitrogen doping is useful for further improving and extending the functionality of carbon-coated nickel oxide nanocomposites.

[0040] In a preferred embodiment, the nanocomposite material of the present application satisfies the following conditions (i) and / or (ii): (i) the carbon element content measured by X-ray photoelectron spectroscopy is about 15 to about 60 mol%, preferably about 15 to about 45 mol%; (ii) the ratio of the carbon element mass content measured by X-ray photoelectron spectroscopy to the carbon element mass content measured by elemental analysis is about 10 or more, preferably about 20 to about 40. As described above, the carbon element content measured by X-ray photoelectron spectroscopy represents the relative carbon element content on the surface of a material measured by quantitative elemental analysis using an X-ray photoelectron spectrometer as the analytical instrument. The carbon element content measured by elemental analysis represents the relative content of the total carbon element in a material measured by quantitative elemental analysis using an elemental analyzer as the analytical instrument. The greater the ratio of the carbon element content measured by X-ray photoelectron spectroscopy to the carbon element content measured by elemental analysis, the more carbon present in the nanocomposite material is localized on the surface of the material. As a result, a shell layer of carbon (and thus a core-shell structure) is formed.

[0041] In some preferred embodiments, the outer shell of the core-shell structure is a nitrogen-doped graphitized carbon film, and the nitrogen content of the nanocomposite material measured by X-ray photoelectron spectroscopy is about 0.1 to 5 mol %. The nitrogen content may be, for example, about 0.1 mol %, about 0.4 mol %, about 2.8 mol %, about 3.6 mol %, about 4.2 mol %, about 4.7 mol %, etc., preferably about 0.5 to 4 mol %, and more preferably about 0.5 to 3 mol %.

[0042] In a preferred embodiment, the Raman spectrum of the nanocomposite material contains a peak at 1580 cm -1 The intensity of the G peak located near 1320 cm -1 The ratio of the intensity of the D peak to that of the nearby D peak is greater than about 2, preferably greater than about 2 and less than about 3. As is well known to those skilled in the art, both the D peak and the G peak are characteristic peaks of carbon crystalline structures in Raman spectra. The D peak represents lattice defects in carbon crystalline structures. The G peak represents sp2 It represents the in-plane stretching vibration of hybrid orbitals. As will be understood, the greater the ratio of the G peak intensity to the D peak intensity, the more graphitic carbon is present in the nanocomposite material relative to amorphous carbon. In the nanocomposite material of the present application, carbon element is present primarily in the form of graphitic carbon. Graphitic carbon has excellent oxidation resistance and can cooperate with the nickel oxide nanoparticles contained in the core to improve catalytic activity. As a result, the performance of the overall composite material is improved.

[0043] In a preferred embodiment, the particle size of the carbon-coated nickel oxide nanoparticles having a core-shell structure is about 1 to 100 nm, preferably about 2 to 40 nm (about 2 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, about 35 nm, about 40 nm, etc.).

[0044] In a second aspect, the present application provides a method for producing a carbon-coated nickel oxide nanocomposite, comprising the steps of: (i) mixing a nickel source, a polybasic organic carboxylic acid, and an optional nitrogen-containing compound in a solvent to form a homogeneous solution; (ii) removing the solvent from the homogeneous solution to obtain a precursor; (iii) pyrolyzing the precursor under an inert or reducing atmosphere; (iv) heat treating the pyrolysis product in the presence of oxygen to obtain a nanocomposite material.

[0045] In the manufacturing method of the present application, elemental nickel is first reacted to form a graphitized carbon layer that tightly coats the outer surface of the elemental nickel. Next, the elemental nickel contained in the inner core is converted to nickel oxide by heat treatment in the presence of oxygen. Simultaneously, amorphous carbon is removed by heat treatment in the presence of oxygen. This results in a nanocomposite of nickel oxide coated with a small amount of graphitic carbon. XRD analysis of the nanocomposite typically reveals only the characteristic peaks of nickel oxide, but not those of elemental nickel. This indicates that the nickel contained in the core of the nanocomposite is substantially in the form of nickel oxide.

[0046] In a specific embodiment, the precursor obtained in step (ii) is an aqueous mixture. This aqueous mixture can be obtained by dissolving the nickel source, the polybasic organic carboxylic acid, and the optional nitrogen-containing compound in a solvent (such as water or ethanol) to form a homogeneous solution, and then evaporating the solvent. The temperature and method for evaporating the solvent may be those used in the prior art. For example, the mixture may be spray-dried at about 80 to 120°C or oven-dried.

[0047] In a preferred embodiment, the nickel source may be one or more of nickel powder, nickel hydroxide, nickel oxide, a soluble organic acid salt of nickel, a basic carbonate salt of nickel, and a carbonate salt of nickel. The soluble organic acid salt of nickel is not particularly limited herein, as long as it can be mixed with a polybasic organic carboxylic acid in a solvent to form a homogeneous solution. The soluble organic acid salt may be a salt of nickel with an organic carboxylic acid that does not contain a heteroatom (e.g., nickel acetate).

[0048] The polybasic organic carboxylic acid is not particularly limited herein as long as it can be mixed with the nickel source in the solvent to form a homogeneous solution. The polybasic organic carboxylic acid may or may not contain nitrogen. Examples of the polybasic organic carboxylic acid may be one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, malic acid, ethylenediaminetetraacetic acid (EDTA), pyridinedicarboxylic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propanediaminetetraacetic acid. Preferably, the dipicolinic acid may be 2,3-dipicolinic acid, 2,4-dipicolinic acid, 2,5-dipicolinic acid, 2,6-dipicolinic acid, 3,4-dipicolinic acid, or 3,5-dipicolinic acid.

[0049] In a preferred embodiment, the nitrogen-containing compound may be one or more selected from the group consisting of urea, melamine, dicyanodiamine, hexamethylenetetramine, and amino acids. It will be understood that if the polybasic organic carboxylic acid is a nitrogen-containing organic carboxylic acid (such as ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propylenediaminetetraacetic acid), the nanocomposite material of the present application having a nitrogen-doped graphitic carbon shell can be obtained without the separate addition of the aforementioned nitrogen-containing compound.

[0050] In some preferred embodiments, in step (i), a nickel source and one or more polybasic organic carboxylic acids selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, and malic acid are mixed in a solvent. The mass ratio of the nickel source to the polybasic organic carboxylic acid is about 1:(0.1 to 100), preferably about 1:(0.1 to 10).

[0051] In some preferred embodiments, in step (i), a nickel source and one or more polybasic organic carboxylic acids selected from the group consisting of ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propanediaminetetraacetic acid are mixed in a solvent. The mass ratio of the nickel source to the polybasic organic carboxylic acid is about 1:(0.1 to 10), preferably about 1:(0.5 to 5).

[0052] In some preferred embodiments, in step (i), a nickel source, a polybasic organic carboxylic acid, and a nitrogen-containing compound are mixed in a solvent. The polybasic organic carboxylic acid is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, and malic acid. The mass ratio of the nickel source, the polybasic organic carboxylic acid, and the nitrogen-containing compound is about 1:(0.1-10):(0.1-10), preferably about 1:(0.5-5):(0.5-5), and more preferably about 1:(0.8-2):(1-2) (e.g., about 1:1:2, about 1:1:1, etc.).

[0053] In a more preferred embodiment, in step (i), another organic compound different from the nickel source, polybasic organic carboxylic acid, and nitrogen-containing compound may be added to form a homogeneous solution. The other organic compound may be any organic compound that does not contain other doping atoms and can supplement the carbon source required in the product. The other organic compound is preferably a non-volatile organic compound (e.g., organic polyol, lactic acid, etc.). In a more preferred embodiment, the mass ratio of the nickel source, polybasic organic carboxylic acid, and other organic compound is about 1:(0.1-10):(0-10), preferably about 1:(0.5-5):(0-5), and more preferably about 1:(0.8-3):(0-3).

[0054] In a preferred embodiment, the pyrolysis in step (iii) comprises heating the precursor to a certain temperature stage in an inert or reducing atmosphere and maintaining the temperature at the certain temperature stage for a certain period of time. Preferred conditions are as follows: the heating rate is about 0.5 to 30°C / min, preferably about 1 to 10°C / min; the certain temperature stage is about 400 to 800°C, preferably 500 to 800°C; and the time to maintain the certain temperature stage is about 20 to 600 minutes, preferably about 60 to 480 minutes. The inert atmosphere is nitrogen or argon, and the reducing atmosphere is a mixture of an inert gas and hydrogen (e.g., an inert atmosphere containing a small amount of hydrogen).

[0055] Without being bound by any theory, the applicant believes that the product obtained after pyrolysis in step (iii) is a nickel nanocomposite coated with a graphitized carbon layer. This "graphitized carbon layer" has a layered carbon structure, not an amorphous carbon structure. This can be clearly observed using a high-resolution transmission electron microscope. The nanocomposite contains nickel nanoparticles tightly coated with a graphitized carbon layer. Therefore, the nickel nanoparticles are substantially prevented from contacting the external environment. The adhesion of the graphitized carbon layer to the nickel surface can be determined using a parameter called "pickling loss." If the adhesion of the graphitized carbon layer to the nickel coating is poor, the nickel will dissolve in the acid during the pickling treatment, resulting in a loss of nickel contained in the core. The greater the pickling loss, the poorer the adhesion of the graphitized carbon layer to the nickel coating. The smaller the pickling loss, the better the adhesion of the graphitized carbon layer to the nickel coating.

[0056] In this application, the pickling treatment conditions typically include treating the sample with an aqueous sulfuric acid solution at 90°C for 8 hours. The concentration of the aqueous sulfuric acid solution is 1 mol / L, and 20 mL of the aqueous sulfuric acid solution is used per gram of sample. After treatment, the sample is washed with deionized water to neutralize it, then dried, weighed, and analyzed. The pickling loss is calculated using the following formula: Pickling loss = [1 - (mass fraction of nickel in the composite material after pickling × mass of the composite material after pickling) ÷ (mass fraction of nickel in the composite material before treatment × mass of the composite material before treatment)] × 100%

[0057] The "composite" in the above formula refers to the composite that has been pyrolyzed via step (iii) but before being heat-treated via step (iv). In a preferred embodiment, the pickling loss of the nanocomposite obtained after pyrolysis in step (iii) is typically 40% or less (e.g., 30% or less, 20% or less, or 10% or less).

[0058] In a preferred embodiment, the heat treatment in step (iv) (also referred to herein as "oxygen treatment") includes introducing an oxygen-containing gas into the pyrolysis product and heating it. The oxygen concentration of the oxygen-containing gas may be about 10 to 40% by volume, preferably about 10 to 20% by volume (e.g., about 10%, about 12%, about 15%, about 17%, about 20%, etc.). Preferably, the oxygen-containing gas contains oxygen and a balance gas. The balance gas may be an inert gas (e.g., nitrogen or argon), preferably nitrogen (but is not limited to these).

[0059] In a preferred embodiment, the temperature of the heat treatment in step (iv) is about 200 to 500° C., preferably about 300 to 400° C. The time of the heat treatment is about 0.5 to 10 hours, preferably about 1 to 10 hours, more preferably about 4 to 8 hours (e.g., about 4 hours, about 5 hours, about 5.5 hours, about 6 hours, about 7 hours, about 7.8 hours).

[0060] As described above, the pyrolysis in step (iii) of the manufacturing method of the present application results in a nanocomposite material in which a nickel core is coated with a graphitic carbon shell. The carbon content of the nanocomposite is approximately 15 to 60 wt. The nickel nanoparticles contained in the nanocomposite material are tightly coated with a graphitic carbon layer, substantially preventing contact with the external environment. As is well known to those skilled in the art, when carbon is brought into contact with oxygen at high temperatures, the carbon is oxidized to generate gas. Therefore, after the heat treatment in step (iv), most of the carbon in the pyrolysis product should be lost through oxidation. However, surprisingly, the inventors of the present application found that, although most of the carbon was burned and the nickel contained in the core was oxidized, some carbon remained in the material obtained after the heat treatment. As described above, detection and analysis using XPS and Raman spectroscopy showed that the remaining carbon was a thin layer of graphitic carbon coating the surface of the nickel oxide. Furthermore, this thin carbon layer provided the nanocomposite material with several excellent properties, particularly catalytic activity. Additionally, the use of nitrogen-containing polybasic organic carboxylic acids and / or nitrogen-containing compounds results in additional small amounts of residual nitrogen remaining in the graphitized carbon film, which is useful for adjusting and controlling the electrochemical properties and surface activity of the material.

[0061] In a third aspect, there is provided a carbon-coated nickel oxide nanocomposite obtainable by the manufacturing method of the present application, the nanocomposite having the characteristics described in the first aspect of the present application, and which will not be described in detail herein for the sake of brevity.

[0062] In a fourth aspect, there is provided a use of the nanocomposite material according to the present application as a catalyst. The nanocomposite material according to the present application has catalytic activity and can be used as a catalyst for various reactions in industrial production. For example, when used as a catalyst, the nanocomposite material can be effectively used in the catalytic decomposition of nitrous oxide and the catalytic combustion of volatile organic compounds, and is expected to have industrial applications.

[0063] In a fifth aspect, the present application provides a method for catalyzing the decomposition of nitrous oxide, comprising contacting nitrous oxide and a catalytic cracking catalyst to produce nitrogen and oxygen; The catalyst comprises the nanocomposite material of the present application as an active component, Preferably, the nanocomposite material of the present application is used as a catalyst.

[0064] In certain embodiments, the method includes flowing a gas comprising nitrous oxide through a reactor loaded with a catalytic cracking catalyst.

[0065] In a preferred embodiment, the catalytic cracking conditions are as follows: the temperature is about 300 to 400°C, preferably about 350 to 380°C; the reaction space velocity is about 1000 to 3000 mL of reaction gas / (hr·catalyst weight (g)). In the present application, a high reaction space velocity can be achieved. This indicates that the application of the nanocomposite material according to the present application in the reaction exhibits high activity, thereby improving the plant's processing capacity.

[0066] According to this application, as described above, the catalysts currently being researched and reported for the decomposition of NO are primarily noble metal catalysts, ion-exchange molecular sieve catalysts, and transition metal oxide catalysts. Noble metal catalysts have low decomposition temperatures, but are expensive and therefore unsuitable for large-scale industrial production. The efficient decomposition temperature for molecular sieve catalysts and transition metal oxide catalysts is 450-550°C, and the high temperature required for the reaction significantly increases industrial costs. In addition, oxygen is generated during the decomposition of nitrous oxide, which can easily deactivate the catalyst. Furthermore, the aggregation of metal active centers at high temperatures can also affect the catalytic performance of these catalysts.

[0067] However, the inventors have found that the use of the carbon-coated nickel oxide nanocomposite material of the present application as a catalyst effectively decomposes nitrous oxide into nitrogen and oxygen, with excellent catalytic activity stability during the reaction. Furthermore, when using existing catalysts to catalyze the decomposition of nitrous oxide, the high-concentration nitrous oxide obtained from industrial production typically needs to be diluted to approximately 0.5-2%. However, the nanocomposite material of the present application has a fast decomposition rate, allowing direct decomposition of nitrous oxide without the need for dilution. For example, when the concentration of nitrous oxide in the reaction gas is approximately 5-40% by volume (e.g., approximately 30-40% by volume), it can be directly catalytically decomposed with a decomposition efficiency of 99% or more, significantly reducing industrial costs. This method has promising prospects for industrial applications.

[0068] In a sixth aspect, the present application provides a method for treating a volatile organic compound, comprising contacting the volatile organic compound with a catalyst for an oxidation reaction, The catalyst comprises the nanocomposite material of the present application as an active component, Preferably, the nanocomposite material of the present application is used as a catalyst.

[0069] In a preferred embodiment, the volatile organic compound is one or more selected from the group consisting of C1 to C4 hydrocarbon compounds, such as n-butane, n-propane, ethane, and / or methane.

[0070] In a preferred embodiment, a mixed gas containing volatile organic compounds and oxygen is brought into contact with a catalytic combustion catalyst to cause an oxidation reaction. Preferably, the mixed gas contains about 0.01 to 2% by volume of volatile organic compounds (e.g., about 0.01% by volume, about 0.05% by volume, about 0.09% by volume, about 0.1% by volume, about 0.15% by volume, about 0.18% by volume, about 0.2% by volume, etc.). The mixed gas contains about 5 to 20% by volume of oxygen (e.g., about 5% by volume, about 10% by volume, about 15% by volume, about 18% by volume, about 20% by volume, etc.). In some further preferred embodiments, the mixed gas may further contain an inert gas (e.g., nitrogen or argon).

[0071] In a preferred embodiment, the space velocity of the oxidation reaction is about 1000-5000 mL of reactant gas / (hr·weight of catalyst (g)). In the present application, high reaction space velocities can be achieved. This indicates that the application of the nanocomposite material of the present application in the reaction exhibits high activity, thereby improving the plant throughput.

[0072] In a preferred embodiment, the temperature of the oxidation reaction is about 300 to 450° C., preferably about 350 to 400° C. This indicates that the use of the nanocomposite material of the present application allows the catalytic oxidation reaction to proceed successfully even at low temperatures.

[0073] According to the present invention, as described above, industrial waste gases often contain volatile organic compounds (VOCs). VOCs are one of the main causes of photochemical smog and, along with nitrogen oxides and respirable particulates, are considered important pollutants in air quality control. Furthermore, VOCs are highly toxic and pose a risk of carcinogenesis. Therefore, there is an urgent need for catalytic oxidation materials with excellent performance for treating VOCs. When the nanocomposite material according to the present application is used in the catalytic combustion of volatile organic compounds, it has excellent catalytic activity and stability, and can efficiently catalyze the oxidative combustion of VOCs at low temperatures. Therefore, the nanocomposite material is useful for solving problems in VOC purification and is of great significance in reducing air pollution.

[0074] In preferred embodiments, the present application provides the following technical solutions: <Item A1> A carbon-coated nickel oxide nanocomposite having a core-shell structure, the core-shell structure comprises an outer shell of graphitic carbon and an inner core containing nickel oxide nanoparticles; The carbon content of the nanocomposite material is 5% by weight or less. Carbon-coated nickel oxide nanocomposite. <Item A2> The nanocomposite material according to item A1, wherein the carbon content of the nanocomposite material is 1% by weight or less. <Item A3> The nanocomposite material according to item A1, wherein the ratio of the carbon element mass content as measured by X-ray photoelectron spectroscopy to the carbon element mass content as measured by elemental analysis is 10 or greater. <Item A4> In the Raman spectrum of the nanocomposite material, -1 The intensity of the G peak located near 1320 cm -1 The nanocomposite material according to item A1, wherein the ratio of the intensity of the D peak to the intensity of the nearby D peak is greater than 2. <Item A5> The nanocomposite material according to item A1, wherein the particle size of the core-shell structure is 1 to 100 nm. <Item A6> A method for producing a carbon-coated nickel oxide nanocomposite material according to any one of items A1 to A5, comprising the following steps: adding a nickel source and a polybasic organic carboxylic acid to a mixing solvent to form a uniform solution; removing the solvent from the homogeneous solution to obtain a precursor; pyrolyzing the precursor in an inert or reducing atmosphere; and Oxygen treatment of the pyrolysis product to obtain said nanocomposite material. <Item A7> The oxygen treatment includes a step of introducing an oxygen-containing gas into the pyrolysis product and heating the gas; the oxygen-containing gas contains oxygen and a balance gas; The oxygen concentration is 10 to 40% by volume. The manufacturing method described in item A6. <Item A8> The temperature of the oxygen treatment is 200 to 500°C, The oxygen treatment time is 0.5 to 10 hours. The manufacturing method described in item A6. <Item A9> the mass ratio of the nickel source to the polybasic organic carboxylic acid is 1:(0.1 to 100); the nickel source is one or more selected from the group consisting of an organic acid salt of nickel, nickel carbonate, basic nickel carbonate, nickel hydroxide, and nickel oxide; The polybasic organic carboxylic acid is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, and malic acid. The manufacturing method described in item A6. <Item A10> The pyrolysis comprises heating the precursor to a certain temperature stage in an inert or reducing atmosphere and maintaining the temperature at the certain temperature stage; The heating rate is 0.5 to 30°C / min. The constant temperature stage is 400 to 800°C, The time for maintaining the constant temperature is 20 to 600 minutes, the inert atmosphere is nitrogen or argon; The reducing atmosphere is a mixed gas of an inert gas and hydrogen. The manufacturing method described in item A6. <Item A11> Use of the nanocomposite material according to any one of items A1 to A5 as a catalyst. <Item A12> Use of the nanocomposite material according to any one of items A1 to A5 as a catalyst for decomposing nitrous oxide, contacting the catalyst and the nitrous oxide for catalytic decomposition to produce nitrogen and oxygen; use. <Item A13> The use according to item A12, wherein the catalytic cracking temperature is 300 to 400°C. <Item A14> The use according to Item A12, wherein the space velocity of the catalytic cracking is 1000 to 3000 mL of reaction gas / (hr·weight of catalyst (g)). <Item A15> The use according to Item A12, wherein the concentration of the nitrous oxide is 30 to 40% by volume. <Item B1> 1. A method for catalytic combustion of volatile organic compounds, comprising the step of catalyzing an oxidation reaction of the volatile organic compounds by using a carbon-coated nickel oxide nanocomposite as a catalyst, The nanocomposite has a core-shell structure, the core-shell structure comprises an outer shell of graphitic carbon and an inner core containing nickel oxide nanoparticles; The carbon content of the nanocomposite material is 5% by weight or less. method. <Item B2> The oxidation reaction includes a step of contacting the mixed gas with a catalytic combustion catalyst, The mixed gas contains a volatile organic compound and a standard gas; The standard gas contains oxygen. The method according to item B1. <Item B3> The mixed gas is The volatile organic compound is contained in an amount of 0.01 to 2% by volume, The oxygen content is 5 to 20% by volume. The method described in item B2. <Item B4> The method according to item B1, wherein the volatile organic compound is one or more selected from the group consisting of hydrocarbon compounds having 1 to 4 carbon atoms. <Item B5> The method according to Item B1, wherein the space velocity of the oxidation reaction is 1000 to 5000 mL of reactant gas / (hr·weight of catalyst (g)). <Item B6> The method according to Item B1, wherein the temperature of the oxidation reaction is 300 to 450°C. <Item B7> The method according to item B1, wherein the carbon content of the nanocomposite material is 1% by weight or less. <Item B8> The method according to item B1, wherein the nanocomposite has a ratio of carbon content as measured by X-ray photoelectron spectroscopy to carbon content as measured by elemental analysis of 10 or greater. <Item B9> In the Raman spectrum of the nanocomposite material, -1 The intensity of the G peak located near 1320 cm -1 The nanocomposite material according to item B1, wherein the ratio of the intensity of the D peak to the intensity of the D peak located nearby is greater than 2. <Item B10> The method according to Item B1, wherein the particle diameter of the core-shell structure is 1 to 100 nm. <Item C1> A carbon-coated nickel oxide nanocomposite having a core-shell structure, the core-shell structure comprises an outer shell of nitrogen-doped graphitic carbon film and an inner core containing nickel oxide nanoparticles; A carbon-coated nickel oxide nanocomposite, wherein the carbon content of the nanocomposite is 5% by weight or less. <Item C2> The nanocomposite material according to item C1, wherein the carbon content of the nanocomposite material is 1% by weight or less. <Item C3> The nanocomposite material according to item C1, wherein the nitrogen element content measured by X-ray photoelectron spectroscopy is 0.1 to 5 mol%. <Item C4> The nanocomposite material according to item C1, wherein the ratio of the carbon element mass content as measured by X-ray photoelectron spectroscopy to the carbon element mass content as measured by elemental analysis is 10 or greater. <Item C5> In the Raman spectrum of the nanocomposite material, -1 The intensity of the G peak located near 1320 cm -1 The nanocomposite material according to item C1, wherein the ratio of the intensity of the D peak to the intensity of the nearby D peak is greater than 2. <Item C6> The nanocomposite material according to item C1, wherein the particle size of the core-shell structure is 1 to 100 nm. <Item C7> A method for producing a carbon-coated nickel oxide nanocomposite material according to any one of Items C1 to C6, comprising the steps of: adding a nickel source and a carboxylic acid to a mixing solvent to form a homogeneous solution; removing the solvent from the homogeneous solution to obtain a precursor; pyrolyzing the precursor in an inert or reducing atmosphere; and treating the pyrolysis product with oxygen to obtain the nanocomposite; Here, the carboxylic acid is a mixture of a polybasic organic carboxylic acid and a nitrogen-containing compound or a nitrogen-containing organic carboxylic acid. <Item C8> The method according to Item C7, further comprising the step of subjecting the pyrolysis product to an acid washing treatment before the oxygen treatment. <Item C9> The manufacturing method according to item C8, wherein the pickling loss of the product after the pickling treatment is 40% or less. <Item C10> The oxygen treatment comprises introducing a standard gas into the pyrolysis product and heating it; The standard gas includes oxygen and a balance gas. The oxygen concentration is 10 to 40% by volume. The manufacturing method described in item C7. <Item C11> The temperature of the oxygen treatment is 200 to 500°C, The oxygen treatment time is 0.5 to 10 hours. The manufacturing method described in item C7. <Item C12> A manufacturing method according to item C7, which satisfies either (i) or (ii) below: (i) the carboxylic acid is a mixture of a polybasic organic carboxylic acid and a nitrogen-containing compound, and the mass ratio of the nickel source, the polybasic organic carboxylic acid, and the nitrogen-containing compound is 1:(0.1 to 10):(0.1 to 10); The carboxylic acid is a nitrogen-containing organic carboxylic acid, and the mass ratio of the nickel source to the nitrogen-containing organic carboxylic acid is 1:(0.1 to 10). <Item C13> the nickel source is one or more selected from the group consisting of nickel powder, nickel hydroxide, nickel oxide, a soluble organic acid salt of nickel, a basic carbonate of nickel, and a carbonate of nickel; the polybasic organic carboxylic acid is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, malic acid, ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propanediaminetetraacetic acid; The nitrogen-containing compound is one or more selected from the group consisting of urea, melamine, dicyanodiamine, hexamethylenetetramine, and amino acids. The manufacturing method described in item C7. <Item C14> The pyrolysis comprises heating the precursor to a certain temperature stage in an inert or reducing atmosphere and maintaining the temperature at the certain temperature stage; The heating rate is 0.5 to 30°C / min. The constant temperature stage is 400 to 800°C, The time for maintaining the constant temperature is 20 to 600 minutes, the inert atmosphere is nitrogen or argon; The reducing atmosphere is a mixed gas of an inert gas and hydrogen. The manufacturing method described in item C7. <Item C15> Use of the nanocomposite material according to any one of items C1 to C6 as an active component of a catalyst in the catalysis of a chemical reaction. <Item C16> 1. A method for catalyzing the decomposition of nitrous oxide, comprising contacting nitrous oxide with a catalytic cracking catalyst to produce nitrogen and oxygen, The catalyst comprises a nanocomposite material according to any one of items C1 to C6. method. <Item C17> In the above catalytic cracking, The reaction temperature is 300 to 400°C. The reaction space velocity is 1000-3000 mL of reactant gas / (hr·weight of catalyst (g)). The concentration of nitrous oxide is 30 to 40% by volume. The method described in item C16. <Item D1> 1. A method for catalytic combustion of volatile organic compounds, comprising catalyzing an oxidation reaction of the volatile organic compounds by use of a catalyst comprising a carbon-coated nickel oxide nanocomposite, The nanocomposite has a core-shell structure, the core-shell structure includes an outer shell that is a nitrogen-doped graphitic carbon film and an inner core that includes nickel oxide nanoparticles; The carbon content of the nanocomposite material is 5% by weight or less. <Item D2> The method according to Item D1, wherein the oxidation reaction comprises a step of contacting a mixed gas containing the volatile organic compound and oxygen with the catalytic combustion catalyst. <Item D3> The mixed gas is The volatile organic compound is contained in an amount of 0.01 to 2% by volume, The oxygen content is 5 to 20% by volume. The method described in item D2. <Item D4> The method according to Item D1, wherein the volatile organic compound is one or more selected from the group consisting of C1 to C4 hydrocarbon compounds. <Item D5> The method according to Item D1, wherein the space velocity of the oxidation reaction is 1000 to 5000 mL of reactant gas / (hr·weight of catalyst (g)). <Item D6> The method according to Item D1, wherein the temperature of the oxidation reaction is 300 to 450°C. <Item D7> The method according to item D1, wherein the carbon content of the nanocomposite material is 1% by weight or less. <Item D8> The nanocomposite material according to item D1, wherein the nitrogen element content measured by X-ray photoelectron spectroscopy is 0.1 to 5 mol%. <Item D9> The nanocomposite material according to item D1, wherein the ratio of carbon element mass content as measured by X-ray photoelectron spectroscopy to carbon element mass content as measured by elemental analysis is 10 or greater. <Item D10> In the Raman spectrum of the nanocomposite material, -1 The intensity of the G peak located near 1320 cm -1 The nanocomposite material of paragraph D1, wherein the ratio of the intensity of the D peak to the intensity of the D peak located nearby is greater than 2. <Item D11> The nanocomposite material according to item D1, wherein the particle size of the core-shell structure is 1 to 100 nm. [Example]

[0075] The present application will be further described with reference to the following examples, but the present application is not limited thereto.

[0076] Unless otherwise stated, reagents used in the examples and comparative examples of this application are of analytical purity.

[0077] In this application, elements on the surface of a material are detected using an X-ray photoelectron spectrometer (XPS). The X-ray photoelectron spectrometer used was an ESCALab220i-XL X-ray photoelectron spectrometer (VG Scientific), equipped with Avantage V5.926 software. The analysis and testing conditions for the X-ray photoelectron spectrometer were as follows: excitation light source: monochromated AlKα radiation, output: 330 W, base vacuum for analysis and testing: 3 x 10 -9 mbar.

[0078] An Elementar Micro Cube elemental analyzer was used for carbon (C) elemental analysis. This instrument is primarily used for analyzing the four elements carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). The operation and conditions were as follows: 1–2 mg of sample was weighed into a tin cup and placed in an automatic sample introduction disk. The sample was passed through a ball valve into a combustion tube and burned at 1000°C (helium gas was purged to prevent atmospheric interference during sample introduction). The combustion gas was then reduced using reduced copper to produce nitrogen, carbon dioxide, and water. The mixed gas was separated using three desorption columns and continuously passed through a TCD detector for detection. Oxygen elemental analysis was performed by converting oxygen in the sample to CO using a carbon catalyst during pyrolysis, followed by CO detection using TCD. Since the composite material of the present invention contains only carbon, nitrogen, and metal oxides, the total metal oxide content can be determined from the carbon and nitrogen element contents.

[0079] The ratio of different metal oxides was measured by X-ray fluorescence spectrometry (XRF). The content of different metal oxides in the composite material was calculated based on the carbon element content. The X-ray fluorescence spectrometer (XRF) used in this application is a Rigaku 3013 X-ray fluorescence spectrometer. The analysis and test conditions for the X-ray fluorescence spectrum were a scan time of 100 seconds and air atmosphere.

[0080] For Raman detection in this application, a LabRAM HR UV-NIR laser confocal Raman spectrometer (Horiba, Ltd.) was used. The laser wavelength was 325 nm.

[0081] The high-resolution transmission electron microscope (HRTEM) used in this application is a JEM-2100 (manufactured by JEOL Ltd.) The test conditions for the high-resolution transmission electron microscope were an acceleration voltage of 200 kV.

[0082] The XRD diffractometer used in this application is an XRD-6000 X-ray powder diffractometer (Shimadzu Corporation). The XRD test conditions were Cu target, Kα radiation (wavelength λ = 0.154 nm), tube voltage: 40 kV, tube current: 200 mA, and scan rate: 10° (2θ) / min.

[0083] Example I-1 This example is provided to illustrate the preparation of carbon-coated nickel oxide nanocomposites according to the present application. (1) 10 g of nickel carbonate and 10 g of citric acid were weighed and added to a beaker containing 100 mL of deionized water. The mixture was stirred at 70°C to obtain a homogeneous solution, and then heated until the solution evaporated to dryness to obtain a solid precursor. (2) The solid precursor obtained in step (1) was placed in a porcelain boat, which was then placed in the constant-temperature zone of a tubular furnace. While introducing nitrogen at a flow rate of 100 mL / min, the mixture was heated at a rate of 4 °C / min up to 600 °C and held at 600 °C for 2 hours. The heating was then stopped, and the mixture was cooled to room temperature under a nitrogen atmosphere to obtain a black solid. The pickling loss of the black solid, measured and calculated using the above method, was 36.7%. (3) The black solid obtained in step (2) was placed in a porcelain boat, which was then placed in the constant temperature zone of a tubular furnace. An oxygen-containing gas (15% oxygen, balance: nitrogen) was introduced at a flow rate of 100 mL / min, and the mixture was heated at a rate of 2°C / min up to 350°C and maintained at 350°C for 8 hours. The heating was then stopped, and the mixture was cooled to room temperature under the oxygen-containing gas atmosphere to obtain a black solid (the nanocomposite material of the present application).

[0084] (Materials Characterization) Figure 1 shows the X-ray diffraction pattern (XRD) of the nanocomposite material of Example I-1. As can be seen from the figure, the nickel contained in the nanocomposite material exists in the form of an oxide after the mild oxidation treatment.

[0085] Figure 2 shows a transmission electron microscope (TEM) image of the nanocomposite material of Example I-1. As can be seen from the figure, the material has a carbon film layer on the surface, and the particle size is about 5 to 20 nm.

[0086] The carbon content of the nanocomposite was 0.64 wt % and the nickel oxide content was 99.36 wt %, as determined by X-ray fluorescence spectroscopy (XRF) and elemental analysis.

[0087] X-ray photoelectron spectroscopy (XPS) analysis detected carbon, oxygen, and nickel as elements in the surface layer of the nanocomposite material. The ratio of the mass content of carbon element in the surface layer to the total mass content of carbon element was 32.7 / 1. This shows that the carbon contained in the material is mainly distributed on the particle surface.

[0088] Figure 3 shows the Raman spectrum of the nanocomposite. -1 ) intensity of the D peak (1320 cm -1 ) to the strength was 2.2 / 1. As can be seen from this, most of the carbon contained in the material is graphite carbon.

[0089] Example I-2 This example is provided to illustrate the preparation of carbon-coated nickel oxide nanocomposites according to the present application. (1) 10 g of nickel acetate and 10 g of citric acid were weighed and added to a beaker containing 100 mL of deionized water. The mixture was stirred at 70°C to obtain a homogeneous solution, and then heated until the solution evaporated to dryness to obtain a solid precursor. (2) The solid precursor obtained in step (1) was placed in a porcelain boat, which was then placed in the constant-temperature zone of a tubular furnace. While introducing nitrogen at a flow rate of 100 mL / min, the mixture was heated at a rate of 2 °C / min up to 650 °C and held at 650 °C for 2 hours. The heating was then stopped, and the mixture was cooled to room temperature under a nitrogen atmosphere to obtain a black solid. The pickling loss of the black solid, measured and calculated using the above method, was 31.9%. (3) The black solid obtained in step (2) was placed in a porcelain boat, which was then placed in the constant temperature zone of a tubular furnace. While introducing an oxygen-containing gas (oxygen: 15%, balance gas: nitrogen) at a flow rate of 100 mL / min, the mixture was heated to 330°C at a rate of 2°C / min and maintained at 330°C for 8 hours. Next, heating was stopped, and the mixture was cooled to room temperature under the oxygen-containing gas atmosphere to obtain a black solid (the nanocomposite material of the present application).

[0090] (Materials Characterization) Figure 4 shows the X-ray diffraction pattern of the nanocomposite material of Example I-2. As can be seen from the figure, the nickel contained in the nanocomposite material exists in the form of an oxide after the mild oxidation treatment.

[0091] Figure 5 shows a transmission electron microscope image of the nanocomposite material of Example I-2. As can be seen from the figure, the material has a carbon film layer on the surface, and the particle size is about 5 to 20 nm.

[0092] The carbon content of the nanocomposite was 0.91 wt % and the nickel oxide content was 99.09 wt %, as determined by X-ray fluorescence spectroscopy (XRF) and elemental analysis.

[0093] X-ray photoelectron spectroscopy (XPS) analysis detected carbon, oxygen, and nickel as elements in the surface layer of the nanocomposite material. The ratio of the mass content of carbon element in the surface layer to the total mass content of carbon element was 22.4 / 1. This shows that the carbon contained in the material is distributed mainly on the particle surface.

[0094] Figure 6 shows the Raman spectrum of the nanocomposite. -1 ) intensity of the D peak (1320 cm -1 ) to the strength was 2.4 / 1. As can be seen from this, most of the carbon contained in the material is graphite carbon.

[0095] [Comparative example I-1] 10 g of nickel acetate solid was placed in a porcelain boat, which was then placed in the constant temperature section of a tubular furnace. While introducing air at a flow rate of 150 mL / min, the material was heated at a rate of 2°C / min up to 500°C and held at 500°C for 2 hours. Next, heating was stopped and the material was cooled to room temperature in an air atmosphere to obtain a sample material.

[0096] Figure 7 shows the X-ray diffraction pattern of the material obtained in Comparative Example I-1. As can be seen from the figure, the XRD pattern of the material shows the characteristic peak of nickel oxide, and nickel is mainly present in the form of nickel oxide.

[0097] Figures 8a and 8b show TEM images at various magnifications of the material obtained in Comparative Example I-1. As can be seen from the figures, nickel oxide is highly aggregated. As can be seen from this, nickel oxide nanoparticles not coated with a carbon film are very prone to aggregation.

[0098] The carbon content of the material obtained in Comparative Example I-1 was 0.12 wt % and the nickel oxide content was 99.88 wt %, as determined by XRF and elemental analysis.

[0099] [Application Example I-1] This application example is provided to illustrate the use of the nanocomposite of Example I-1 as a catalyst for the catalytic decomposition of nitrous oxide.

[0100] 0.5 g of catalyst was loaded into a continuous-flow fixed-bed reactor and a mixed gas (NO: 38.0 vol%, balance: nitrogen) was introduced at a flow rate of 15 mL / min. Activity was evaluated at temperatures between 300 and 500 °C. The conversion of NO catalytically decomposed by the catalyst at different temperatures is shown in Table I-1.

[0101] [Application Example I-2] N2O was decomposed as described in Application Example I-1, except that the nanocomposite material of Example I-2 was used as the catalyst. The results are shown in Table I-1.

[0102] [Comparative Application Example I-1] N2O was decomposed in the same manner as in Application Example I-1, except that the material of Comparative Example I-1 was used as the catalyst. The results are shown in Table I-1.

[0103] [Comparative Application Example I-2] N2O was decomposed as described in Application Example I-1, except that commercially available nickel oxide (NiO, analytical grade purity, batch number: 20160803, manufacturer: Sinopharm Chemical Reagent Company Limited) was used as the catalyst. The results are shown in Table I-1.

[0104] [Table 1]

[0105] As can be seen from Table I-1 above, the carbon-coated nickel oxide nanocomposite material of the present application exhibited superior catalytic performance for NO decomposition to uncoated pure nickel oxide, and was able to catalyze the decomposition of NO with high efficiency at a relatively low temperature. The material of Comparative Example I-1 required temperatures of 490°C or higher to achieve an NO conversion rate of over 99%. Commercially available nickel oxides required relatively high decomposition temperatures.

[0106] The nanocomposite material of the present application exhibits excellent catalytic performance for the decomposition of nitrous oxide and can be used for the effective decomposition and removal of NO at low temperatures. Therefore, the use of the nanocomposite material in the treatment of NO contained in industrial waste gases, such as the treatment of high-concentration NO tail gases generated in the production processes of adipic acid and nitric acid plants, can significantly reduce reaction temperatures and energy consumption. Therefore, the nanocomposite material of the present application has promising prospects for industrial applications.

[0107] [Application Example I-3] This application example is provided to illustrate the use of the nanocomposite of Example I-1 as a catalyst for the catalytic combustion of VOCs.

[0108] 0.2 g of catalyst was loaded into a continuous-flow fixed-bed reactor and a mixed gas (n-butane: 0.5 vol.%, oxygen: 8 vol.%, balance: nitrogen) was introduced at a flow rate of 15 mL / min. Activity was evaluated at temperatures between 300 and 500 °C. The conversion rates of VOCs catalytically combusted over the catalyst at different temperatures are shown in Table 1-2.

[0109] [Application Example I-4] The VOCs were catalytically combusted as described in Application Example I-3, except that the nanocomposite material of Example I-2 was used as the catalyst. The results are shown in Table I-2.

[0110] [Comparative Application Example I-3] VOCs were catalytically combusted as described in Application Example I-3, except that the material of Comparative Example I-1 was used as the catalyst. The results are shown in Table I-2.

[0111] [Comparative Application Example I-4] VOCs were catalytically combusted as described in Application Example I-3, except that commercially available nickel oxide (NiO, analytical grade purity, batch number: 20160803, manufacturer: Sinopharm Chemical Reagent Company Limited) was used as the catalyst. The results are shown in Table I-2.

[0112] [Table 2]

[0113] As can be seen from Table I-2 above, in catalytic combustion evaluation experiments using n-butane as a model molecule, the carbon-coated nickel oxide nanocomposite of the present application exhibited superior catalytic performance for the combustion of VOCs compared to uncoated pure nickel oxide. Uncoated nickel oxide catalysts required temperatures of 500°C or higher to completely combust n-butane. The material of the present application can efficiently catalyze the complete combustion of n-butane to produce carbon dioxide and water at temperatures between 350 and 400°C. This significantly reduces reaction temperature and energy consumption. Therefore, the nanocomposite of the present application has promising prospects for industrial applications.

[0114] Example II-1 This example is provided to illustrate the preparation of the nitrogen-doped carbon-coated nickel oxide nanocomposite material of the present application. (1) 10 g of nickel acetate, 10 g of citric acid, and 20 g of hexamethylenetetramine were added to 100 mL of deionized water. The mixture was stirred at 70°C to obtain a homogeneous solution, and then further heated until the solution evaporated to dryness to obtain a solid precursor. (2) The precursor was placed in a porcelain boat, which was then placed in the constant-temperature zone of a tubular furnace. While introducing nitrogen at a flow rate of 100 mL / min, the material was heated at a rate of 5 °C / min up to 550 °C and held at 550 °C for 2 hours. The heating was then stopped, and the material was cooled to room temperature under a nitrogen atmosphere to obtain a black solid. The pickling loss of the black solid, measured and calculated using the above method, was 17.6%. (3) The black solid obtained in step (2) was placed in a porcelain boat, which was then placed in the constant temperature zone of a tubular furnace. An oxygen-containing gas (oxygen: 15% by volume, balance gas: nitrogen) was introduced at a flow rate of 100 mL / min, and the mixture was heated at a rate of 2°C / min up to 320°C and maintained at 320°C for 8 hours. Next, heating was stopped, and the mixture was cooled to room temperature under the oxygen-containing gas atmosphere to obtain a black solid (nitrogen-doped carbon-coated nickel oxide nanocomposite material of the present application).

[0115] Figure 9 shows the X-ray diffraction pattern (XRD) of the nitrogen-doped carbon-coated nickel oxide nanocomposite, and Figure 10 shows a TEM image of the nanocomposite. As can be seen from Figure 9, the nickel contained in the nanocomposite material exists in the form of oxide after mild oxidation treatment, and as can be seen from Figure 10, the particle size of the nanocomposite material is about 5-20 nm.

[0116] As determined by elemental analysis, the carbon content of the nanocomposite was 0.82 wt%, the nitrogen content was 0.01 wt%, and the nickel oxide content was 99.17 wt%.

[0117] XPS analysis detected carbon, nitrogen, oxygen, and nickel as elements in the surface layer of the nanocomposite material. The nitrogen content in the surface layer was 1.04 mol%. The ratio of the mass content of carbon element in the surface layer to the total mass content of carbon element was 29.6 / 1. This shows that the carbon contained in the material is mainly present on the particle surface, and the carbon layer is doped with nitrogen.

[0118] FIG. 11 shows the Raman spectrum of the carbon-coated nickel oxide nanocomposite of Example II-1. The G peak (1580 cm -1 ) intensity of the D peak (1320 cm -1 ) to the strength was 2.1 / 1. As can be seen from this, most of the carbon contained in the material is graphite carbon.

[0119] Example II-2 This example is provided to illustrate the preparation of the nitrogen-doped carbon-coated nickel oxide nanocomposite material of the present application. (1) 20 g of nickel acetate and 10 g of ethylenediaminetetraacetic acid were added to 150 mL of deionized water. The mixture was stirred at 60°C and reacted for 24 hours, then heated until the solution evaporated to dryness. The resulting solid was pulverized to obtain a solid precursor. (2) The precursor was placed in a porcelain boat, which was then placed in the constant-temperature zone of a tubular furnace. While introducing nitrogen at a flow rate of 100 mL / min, the material was heated at a rate of 4 °C / min up to 600 °C and held at 600 °C for 2 hours. The heating was then stopped, and the material was cooled to room temperature under a nitrogen atmosphere to obtain a black solid. The pickling loss of the black solid, measured and calculated using the above method, was 21.7%. (3) The black solid obtained in step (2) was placed in a porcelain boat, which was then placed in the constant temperature zone of a tubular furnace. While introducing an oxygen-containing gas (oxygen: 15% by volume, balance gas: nitrogen) at a flow rate of 100 mL / min, the mixture was heated at a rate of 2°C / min up to 320°C and maintained at 320°C for 8 hours. Next, heating was stopped, and the mixture was cooled to room temperature under the oxygen-containing gas atmosphere to obtain a black solid (nitrogen-doped carbon-coated nickel oxide nanocomposite material of the present application).

[0120] Figure 12 shows the X-ray diffraction pattern (XRD) of the nitrogen-doped carbon-coated nickel oxide nanocomposite. Figure 13 shows a TEM image of the composite. As can be seen from Figure 12, the nickel contained in the nanocomposite exists in the form of an oxide after mild oxidation treatment. As can be seen from Figure 13, the particle size of the nanocomposite is about 5-20 nm.

[0121] As determined by elemental analysis, the carbon content of the nanocomposite was 0.62 wt%, the nitrogen content was 0.01 wt%, and the nickel oxide content was 99.37 wt%.

[0122] XPS analysis detected carbon, nitrogen, oxygen, and nickel as elements in the surface layer of the nanocomposite. The nitrogen content in the surface layer was 0.91 mol%. The ratio of the mass content of carbon elements in the surface layer to the total mass content of carbon elements was 26.9 / 1. This shows that the carbon contained in the nanocomposite is mainly distributed on the particle surface, and the carbon layer is doped with nitrogen.

[0123] FIG. 14 shows the Raman spectrum of the carbon-coated nickel oxide nanocomposite of Example II-2. The G peak (1580 cm -1 ) intensity of the D peak (1320 cm -1 ) to the strength was 2.4 / 1. As can be seen from this, most of the carbon contained in the material is graphite carbon.

[0124] [Application Example II-1] This application example is provided to illustrate the use of the nanocomposite material of Example II-1 to catalyze the decomposition of nitrous oxide.

[0125] 0.5 g of catalyst was loaded into a continuous-flow fixed-bed reactor, and a mixed gas (NO: 38.0 vol%, balance gas: nitrogen) was introduced at a flow rate of 15 mL / min. Activity was evaluated in the temperature range shown in Table II-1. The conversion of NO catalytically decomposed by the catalyst at each temperature is shown in Table II-1.

[0126] [Application Example II-2] N2O was decomposed as described in Application Example II-1, except that the nanocomposite material of Example II-2 was used as the catalyst. The results are shown in Table II-1.

[0127] [Table 3]

[0128] As can be seen from Table II-1 above, the nitrogen-doped carbon-coated nickel oxide nanocomposite of the present application exhibited better catalytic performance for the decomposition of NO than uncoated pure nickel oxide, and could effectively catalyze the decomposition of NO at relatively low temperatures.

[0129] [Application Example II-3] This application example is provided to illustrate the use of the nanocomposite of Example II-1 as a catalyst for the catalytic combustion of VOCs.

[0130] 0.2 g of catalyst was loaded into a continuous-flow fixed-bed reactor, and a mixed gas (n-butane: 0.5 vol.%, oxygen: 8.0 vol.%, balance gas: nitrogen) was introduced at a flow rate of 15 mL / min. Activity was evaluated over the temperature range shown in Table II-2. The conversion rates of VOCs catalytically combusted over the catalyst at each temperature are shown in Table II-2.

[0131] [Application Example II-4] The examples of this application are provided to illustrate the use of the nanocomposite of Example II-2 as a catalyst for the catalytic combustion of VOCs.

[0132] 0.5 g of catalyst was loaded into a continuous-flow fixed-bed reactor, and a mixed gas (n-butane: 0.2 vol.%, oxygen: 8.0 vol.%, balance gas: nitrogen) was introduced at a flow rate of 15 mL / min. Activity was evaluated over the temperature range shown in Table II-2. The conversion rates of VOCs catalytically combusted over the catalyst at each temperature are shown in Table II-2.

[0133] [Table 4]

[0134] As can be seen from Table II-2 above, in catalytic combustion evaluation experiments using n-butane as a model molecule, the nitrogen-doped carbon-coated nickel oxide nanocomposite of the present application exhibited superior catalytic performance for the combustion of VOCs than uncoated pure nickel oxide.

[0135] In the foregoing description, the inventive concepts of the present application have been described with reference to specific embodiments. However, it is to be understood that various modifications and changes can be made without departing from the scope of the present application as set forth in the appended claims. Accordingly, the description and drawings should be interpreted in an illustrative manner and not in a restrictive sense. All such modifications and changes are intended to be included within the scope of the present application.

Claims

1. 1. A carbon-coated nickel oxide nanocomposite comprising carbon-coated nickel oxide nanoparticles having a core-shell structure, The core-shell structure has an outer shell that is a graphitized carbon film (optionally doped with nitrogen) and an inner core that contains nickel oxide nanoparticles; the nanocomposite has a carbon content of greater than 0 wt.% and less than or equal to 5 wt.%, based on the weight of the nanocomposite; The graphitized carbon film means a thin film structure mainly composed of graphitized carbon. Nanocomposites.

2. 10. The nanocomposite material of claim 1, which satisfies the following (i) and / or (ii): (i) the carbon element content measured by X-ray photoelectron spectroscopy is 15 to 60 mol%; (ii) the ratio of the elemental carbon mass content of said nanocomposite as determined by X-ray photoelectron spectroscopy to the elemental carbon mass content as determined by elemental analysis is greater than or equal to 10;

3. In the Raman spectrum of the nanocomposite material, －１ The intensity of the G peak located near 1320 cm －１ The ratio of the intensity of the D peak to that of the nearby D peak is greater than 2.

3. The nanocomposite material of claim 1 or 2.

4. the outer shell of the core-shell structure is a nitrogen-doped graphitic carbon film; The nitrogen element content of the nanocomposite material is 0.1 to 5 mol% as measured by X-ray photoelectron spectroscopy. The nanocomposite material according to any one of claims 1 to 3.

5. The particle size of the carbon-coated nickel oxide nanoparticles is 1 to 100 nm. The nanocomposite material according to any one of claims 1 to 4.

6. A method for producing a carbon-coated nickel oxide nanocomposite, comprising the steps of: (i) mixing a nickel source, a polybasic organic carboxylic acid, and an optional nitrogen-containing compound in a solvent to form a homogeneous solution; (ii) removing the solvent from the homogeneous solution to obtain a precursor; (iii) pyrolyzing the precursor under an inert or reducing atmosphere; (iv) heat treating the pyrolysis product in the presence of oxygen to obtain a nanocomposite material.

7. The heat treatment in step (iv) includes a step of introducing an oxygen-containing gas into the pyrolysis product and heating the pyrolysis product; The oxygen concentration of the oxygen-containing gas is 10 to 40% by volume, The temperature of the heat treatment is 200 to 500°C, The heat treatment time is 0.5 to 10 hours. The method of claim 6.

8. In the step (i), a polybasic organic carboxylic acid, which is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, and malic acid, is mixed with the nickel source in the solvent; the mass ratio of the nickel source to the polybasic organic carboxylic acid is 1:(0.1 to 100); The method according to claim 6 or 7.

9. In the step (i), one or more polybasic organic carboxylic acids selected from the group consisting of ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propylenediaminetetraacetic acid are mixed with the nickel source in the solvent; the mass ratio of the nickel source to the polybasic organic carboxylic acid is 1:(0.1 to 10); The method according to claim 6 or 7.

10. In the step (i), a polybasic organic carboxylic acid, which is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, and malic acid, the nickel source, and the nitrogen-containing compound are mixed in the solvent; the mass ratio of the nickel source to the polybasic organic carboxylic acid to the nitrogen-containing compound is 1:(0.1 to 10):(0.1 to 10); The method according to claim 6 or 7.

11. The pyrolysis of step (iii) comprises heating the precursor to a certain temperature stage in an inert or reducing atmosphere and maintaining the temperature at the certain temperature stage for a certain period of time; The heating rate is 0.5 to 30°C / min. the temperature of the constant temperature stage is 400 to 800°C; The time for maintaining the constant temperature stage is 20 to 600 minutes, the inert atmosphere is nitrogen or argon; The reducing atmosphere is a mixed gas of an inert gas and hydrogen. The method according to any one of claims 6 to 10.

12. 1. A method for catalyzing the decomposition of nitrous oxide, comprising contacting nitrous oxide with a catalytic cracking catalyst to produce nitrogen and oxygen, The catalyst comprises the nanocomposite material according to any one of claims 1 to 5 as an active component. method.

13. 13. The method of claim 12, wherein the catalytic cracking conditions satisfy: Reaction temperature: 300-400°C; Reaction space velocity: 1000 to 3000 mL of reaction gas / (hr·catalyst weight (g)); Volume concentration of nitrous oxide in the reaction gas: 5 to 40%.

14. A method for treating a volatile organic compound, comprising a step of contacting the volatile organic compound with a catalyst for oxidation reaction, The catalyst comprises the nanocomposite material according to any one of claims 1 to 5 as an active component. method.

15. a mixed gas containing the volatile organic compounds and oxygen is brought into contact with an oxidation reaction catalyst to cause an oxidation reaction; The mixed gas contains 0.01 to 2 volume % of a volatile organic compound and 5 to 20 volume % of oxygen.

15. The method of claim 14.

16. 16. The method according to claim 14 or 15, wherein the conditions for the oxidation reaction satisfy the following: Reaction temperature: 300-450°C; Reaction space velocity: 1000 to 5000 mL of reaction gas / (hr·catalyst weight (g)).

17. the nickel source is one or more selected from the group consisting of nickel powder, nickel hydroxide, nickel oxide, a soluble organic acid salt of nickel, a basic carbonate of nickel, and a carbonate of nickel; the polybasic organic carboxylic acid is one or more selected from the group consisting of citric acid, maleic acid, trimesic acid, terephthalic acid, gluconic acid, malic acid, ethylenediaminetetraacetic acid, dipicolinic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, and 1,3-propanediaminetetraacetic acid; The nitrogen-containing compound is one or more selected from the group consisting of urea, melamine, dicyanodiamine, hexamethylenetetramine, and amino acids. The method of claim 6.

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