CN106925317B - A kind of carbon-based catalytic material and its synthesis method - Google Patents

Abstract

The invention discloses a carbon-based material. Based on the total weight of the carbon-based material, the carbon-based material contains 60-99% by weight of carbon element, 0.1-16% by weight of nitrogen element, and 0.5-20% by weight of nitrogen element. Oxygen and 0.05-8 wt% metal elements. The present invention also provides a method for preparing the above carbon-based material, the method comprising the following steps: (1) mixing a solid carbon source, a precursor and water to obtain a mixed material; wherein, the precursor contains an organic base source and an inorganic alkali source; (2) hydrothermally treat the mixed material to obtain a hydrothermally treated material; and separate and dry the solid in the hydrothermally treated material to obtain a dried material; (3) The dried material is calcined. The present invention also provides the use of the carbon-based material as described above in catalyzing hydrocarbon oxidation reactions. The present invention can simultaneously improve the selectivity and conversion rate of hydrocarbon oxidation to prepare olefins.

Description

A kind of carbon-based catalytic material and its synthesis method

technical field

The present invention relates to the field of material chemistry, in particular, to a carbon-based material, a method for preparing the carbon-based material and the use of the carbon-based material.

Background technique

Carbon-based materials include carbon nanotubes, graphene, fullerenes, carbon nanofibers, and nanodiamonds, among others. Carbon-based materials can be used as catalytic materials for oxidizing hydrocarbons, especially alkanes. For example, there are literatures (Applied Catalysis, 29 (1987) 311-326) that reported the use of activated carbon as a catalyst to oxidatively dehydrogenate ethylbenzene into styrene, and literature (ACTAPHYSICA POLONIC A, 118 (2010) 459-464) reported the conversion of n-butane to butene and butadiene using activated carbon as a catalyst.

Studies have shown that if saturated and unsaturated functional groups containing heteroatoms such as oxygen and nitrogen are modified on the surface of carbon nanomaterials (such as carbon nanotubes and graphene), the catalytic activity of carbon nanomaterials can be changed. Oxidation treatment is performed to introduce oxygen atoms into the carbon nanomaterials, thereby increasing the content of oxygen-containing functional groups in the carbon nanomaterials. For example, the carbon nanomaterials can be subjected to reflux reaction in strong acid (such as HNO ₃ , H ₂ SO ₄ ) and/or strong oxidizing solution (such as H ₂ O ₂ , KMnO ₄ ), and the reflux reaction can also be assisted during the reflux reaction. Microwave heating or ultrasonic vibration to enhance the effect of the oxidation reaction.

However, the reflux reaction in strong acid and/or strong oxidizing solution may adversely affect the framework structure of carbon nanomaterials, or even destroy the framework structure of carbon nanomaterials. For example, by oxidizing carbon nanomaterials with nitric acid, although a large number of oxygen-containing functional groups can be introduced on the surface of carbon nanomaterials, it is very easy to cause the carbon nanomaterials to be cut off and/or significantly increase the defect sites in the graphite network structure, which may reduce the nanometer size. Properties of carbon materials, such as thermal stability. In addition, when oxygen atoms are introduced by conducting a reflux reaction in a strong acid and/or a strong oxidizing solution, the introduction amount of oxygen atoms is highly dependent on the reaction operating conditions, has a wide fluctuation range, and is difficult to precisely control.

Olefins, especially diolefins and aromatic olefins, are important chemical raw materials. For example, butadiene is the main raw material for the production of synthetic rubbers (such as styrene-butadiene rubber, butadiene rubber, nitrile rubber, and neoprene rubber). The copolymerization of styrene and butadiene is used to produce various resins with a wide range of uses (such as ABS resin, SBS resin, BS resin and MBS resin), so that butadiene gradually occupies an important position in resin production. In addition, butadiene can also be used to produce ethylidene norbornene (the third monomer of ethylene-propylene rubber), 1,4-butanediol, adiponitrile (monomer of nylon 66), sulfolane, anthraquinone and tetrahydrofuran, etc. Therefore, butadiene is also an important basic chemical raw material. In addition, styrene is also an important monomer for synthetic rubber and plastics, which can be used to produce styrene-butadiene rubber, polystyrene and foamed polystyrene, etc. It is also used to copolymerize with other monomers to manufacture engineering plastics for various purposes. For example, ABS resin obtained by copolymerization with acrylonitrile and butadiene is widely used in various household appliances and industries; SAN resin obtained by copolymerization with acrylonitrile is a resin with impact resistance and bright color; The obtained SBS is a thermoplastic rubber, which is widely used as a modifier of polyvinyl chloride and polypropylene. Styrene is mainly used in the production of styrene series resins and styrene-butadiene rubber, and is also one of the raw materials for the production of ion exchange resins and pharmaceuticals. In addition, styrene can also be used in industries such as pharmaceuticals, dyes, pesticides, and mineral processing.

Oxidative dehydrogenation of hydrocarbons is an important method for preparing olefins. For example, butane can be oxidatively dehydrogenated to 1-butene, and 1-butene can be further oxidatively dehydrogenated to 1,3-butadiene; Dehydrogenation produces styrene. However, when oxidative dehydrogenation of hydrocarbons is used to prepare olefins, there is a common problem that the selectivity and conversion are difficult to improve at the same time.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problem that it is generally difficult to simultaneously improve the selectivity and conversion rate in the oxidative dehydrogenation of hydrocarbons to prepare olefins, and to provide a carbonaceous material that can catalyze the oxidative dehydrogenation of hydrocarbons to prepare olefins and simultaneously obtain high selectivity and conversion rate. Base material, preparation method of the carbon-based material and use of the carbon-based material.

The inventors of the present invention have found that the carbon source material is hydrothermally treated with a precursor containing an organic alkali source and an inorganic alkali source. The activity of olefins and at the same time obtaining carbon-based materials with high selectivity and conversion yields the present invention.

In one aspect, the present invention provides a carbon-based material, based on the total weight of the carbon-based material, the carbon-based material contains 60-99 wt % carbon element, 0.1-16 wt % nitrogen element, 0.5-20 wt % % by weight of oxygen and 0.05-8% by weight of metal elements; wherein, the metal elements include at least one of alkali metal elements and/or alkaline earth metal elements, and in the X-ray photoelectron spectrum of the carbon-based material, 533.1 The ratio of the amount of oxygen element determined by the peak in the range of -533.5 eV to the amount of oxygen element determined by the peak in the range of 531.8-532.2 eV is in the range of 1-10.

On the other hand, the present invention also provides a method for preparing a carbon-based material, the method comprising the following steps: (1) mixing a solid carbon source, a precursor and water to obtain a mixed material; wherein, the precursor Contains an organic alkali source and an inorganic alkali source, the organic alkali source includes an organic amine and/or a quaternary ammonium base; the inorganic alkali source includes a hydroxide of a metal element and/or a salt of an alkaline metal element; the Metal elements include at least one of alkali metal elements and/or alkaline earth metal elements; (2) hydrothermal treatment is performed on the mixed material obtained in step (1) to obtain a hydrothermally treated material; and the hydrothermally treated material is separated (3) calcining the solid in the hydrothermally treated material obtained in step (2).

On the other hand, the present invention also provides the carbon-based material prepared by the above method.

In another aspect, the present invention also provides the carbon-based material as described above and the use of the carbon-based material prepared by the above-described method in catalyzing hydrocarbon oxidation.

Through the above technical solutions, the present invention can simultaneously improve the selectivity and conversion rate of hydrocarbon oxidation to prepare olefins.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The invention provides a carbon-based material, based on the total weight of the carbon-based material, the carbon-based material contains 60-99 wt % of carbon element, 0.1-16 wt % of nitrogen element, 0.5-20 wt % of carbon element Oxygen element and 0.05-8% by weight of metal elements, the metal elements include at least one of alkali metal elements and/or alkaline earth metal elements; wherein, in the X-ray photoelectron spectrum of the carbon-based material, 533.1-533.5 eV The ratio of the amount of oxygen element determined by the peak in the range to the amount of oxygen element determined by the peak in the range of 531.8-532.2 eV is in the range of 1-10.

Wherein, preferably, in the X-ray photoelectron spectrum of the carbon-based material, the ratio of the amount of oxygen determined by the peak in the range of 533.1-533.5 eV to the amount of oxygen determined by the peak in the range of 531.8-532.2 eV is 1.2 -5 range. Further preferably, in the X-ray photoelectron spectrum of the carbon-based material, the ratio of the amount of oxygen determined by the peak in the range of 533.1-533.5 eV to the amount of oxygen determined by the peak in the range of 531.8-532.2 eV is 1.5- within the range of 2.5. The total amount of O in the carbon-based material can be determined from the area of the O1s peak in the X-ray photoelectron spectrum. Among them, the amount of oxygen elements determined by the peak in the range of 533.1-533.5eV can indicate the relative molar content of C-O groups, and the amount of oxygen elements determined by the peak in the range of 531.8-532.2eV can indicate the relative moles of C=O groups. content.

In the present invention, the content of each element in the carbon-based material is the value determined by X-ray photoelectron spectroscopy after drying the carbon-based material in a helium atmosphere at a temperature of 300° C. for 3 hours, and the determination method is in the art It is well known to the skilled person and will not be repeated here.

In the present invention, the X-ray photoelectron spectrum spectrum refers to the XPS spectrum, and the XPS spectrum can be measured according to conventional methods in the field of instrumental analysis. The calculation can be performed by conventional methods in the field. For example, the measurement can be performed according to the instructions of the X-ray photoelectron spectrometer and the quantitative calculation can be performed by using the data software provided by the X-ray photoelectron spectrometer, which is not specially required in the present invention. The X-ray photoelectron spectroscopy data of the carbon-based material were all measured after the samples were treated in a helium atmosphere at a temperature of 300°C for 3 hours. However, when the measured content value is less than 0.1% by weight, the content of the element is described as 0.

In the present invention, from the viewpoint of further improving the catalytic ability of the carbon-based material, preferably, based on the total weight of the carbon-based material, the carbon-based material contains 80-98 wt % of carbon elements, 0.2-8 % by weight nitrogen, 1-10% by weight oxygen and 0.1-4% by weight metal. More preferably, the carbon-based material contains 85-95 wt % carbon element, 0.5-6 wt % nitrogen element, 3-8 wt % oxygen element and 0.2-3 wt % metal element.

In the present invention, preferably, in the X-ray photoelectron spectrum of the carbon-based material, the amount of oxygen determined by the peak in the range of 529.5-530.8 eV accounts for the ratio of the amount of oxygen determined by the peak in the range of 526.0-535.0 eV In the range of 0.01-0.1, more preferably in the range of 0.03-0.08. Among them, the amount of oxygen element determined by the peak in the range of 529.5-530.8eV can basically indicate the relative molar content of oxygen contained in the metal-oxygen bond group in the carbon-based material, and the oxygen element determined by the peak in the range of 526.0-535.0eV The amount of can basically indicate the relative molar content of oxygen contained in all oxygen-containing groups of the carbon-based material.

According to the carbon-based material of the present invention, in the X-ray photoelectron spectrum of the carbon-based material, the amount of nitrogen element determined by the peak in the range of 398.0-400.5 eV and the amount of nitrogen element determined by the peak in the range of 395.0-405.0 eV The ratio is in the range of 0.5-0.85; more preferably in the range of 0.6-0.75. The total amount of nitrogen in the carbon-based material can be determined by the area of the N1s spectral peak in the X-ray photoelectron spectrum. Generally, the amount of nitrogen determined by the peak in the range of 395.0-405.0eV can basically indicate the total amount of nitrogen in the carbon-based material. The relative molar content of nitrogen contained in a nitrogen-containing group. Among them, the amount of nitrogen element determined by the peak in the range of 398.0-400.5 eV can basically indicate the relative molar content of nitrogen contained in the NH group in the carbon-based material (such as nitrogen in pyrrole, pyridine, amide and surface amino group).

According to the carbon-based material of the present invention, in the X-ray photoelectron spectrum of the carbon-based material, the amount of nitrogen element determined by the peak in the range of 400.6-401.5 eV and the amount of nitrogen element determined by the peak in the range of 395.0-405.0 eV The ratio is in the range of 0.15-0.5; more preferably in the range of 0.25-0.4. Among them, the amount of nitrogen determined by the peak in the range of 400.6-401.5eV can basically indicate the relative molar content of graphitic nitrogen contained in the carbon-based material, and the amount of nitrogen determined by the peak in the range of 395.0-405.0eV can basically indicate The relative molar content of nitrogen contained in all nitrogen-containing groups of a carbon-based material.

According to the carbon-based material of the present invention, in the X-ray photoelectron spectrum of the carbon-based material, the amount of carbon element determined by the peak in the range of 283.8-284.2 eV and the amount of carbon element determined by the peak in the range of 280.0-294.0 eV are the same The ratio is in the range of 0.6-1; more preferably in the range of 0.7-0.9. Among them, the amount of carbon element determined by the peak in the range of 283.8-284.2eV can basically indicate the relative molar content of graphitic carbon contained in the carbon-based material, and the amount of carbon element determined by the peak in the range of 280.0-294.0eV can basically indicate The relative molar content of carbon contained in all carbon-containing groups of a carbon-based material.

According to the carbon-based material of the present invention, in the X-ray photoelectron spectrum of the carbon-based material, the amount of carbon element determined by the peak in the range of 286.2-286.6 eV and the amount of carbon element determined by the peak in the range of 288.6-289.0 eV The ratio of the sum to the amount of carbon element determined by the peak in the range of 280.0-294.0 eV is in the range of 0.02-0.2; more preferably, it is in the range of 0.05-0.15. The total amount of C elements in the carbon-based material can be determined by the area of the C1s spectrum peak in the X-ray photoelectron spectrum. Generally, the amount of carbon elements determined by the peak in the range of 280.0-294.0eV can basically indicate all the carbon-based materials. The relative molar content of carbon contained in a carbon-containing group. Among them, the amount of carbon element determined by the peak in the range of 286.2-286.6eV can basically indicate the relative molar content of carbon contained in the C-O group in the carbon-based material (such as carbon in carboxyl group, anhydride and ester), 288.6-289.0eV The amount of carbon element determined by the peaks within the range can basically indicate the relative molar content of carbon contained in the C=O group in the carbon-based material (eg, carbon in hydroxyl and ether).

According to the carbon-based material of the present invention, in the X-ray photoelectron spectrum of the carbon-based material, the amount of carbon element determined by the peak in the range of 286.2-286.6 eV and the amount of carbon element determined by the peak in the range of 288.6-289.0 eV are the same The ratio is in the range of 0.3-2; more preferably in the range of 0.6-1.7.

In the present invention, the positions of the above-mentioned peaks are determined by the binding energy corresponding to the peak top of the peak, and the peak determined by the above-mentioned range refers to the peak whose binding energy corresponding to the peak top is within this range. can include one peak or two or more peaks. For example, a peak in the range of 280.0-294.0 eV refers to all peaks whose binding energy corresponding to the peak top is in the range of 280.0-294.0 eV.

According to the carbon-based material of the present invention, the W ₅₀₀ /W ₈₀₀ of the carbon-based material may be in the range of 0.02-0.5; preferably, the W ₅₀₀ /W ₈₀₀ of the carbon-based material is in the range of 0.05-0.25 . In this preferred case, when the carbon-based material is used as a catalyst, a better catalytic effect can be obtained, especially when used as a catalyst for the dehydrogenation reaction of hydrocarbons, a higher feedstock conversion rate and product selectivity can be obtained . Wherein, W ₈₀₀ refers to the reduction rate of the weight of the carbon-based material at 800°C relative to the weight at 400°C under the condition of air atmosphere and an initial temperature of 25°C and a temperature rise of 10°C/min, that is (the The difference between the weight of the carbon-based material at 400°C and the weight of the carbon-based material at 800°C)/the weight of the carbon-based material at 400°C, W ₅₀₀ refers to the air atmosphere and the initial temperature of 25°C and 10 Under the heating condition of ℃/min, the reduction rate of the weight of the carbon-based material at 500 ℃ relative to the weight at 400 ℃, that is (the weight of the carbon-based material at 400 ℃ and the carbon-based material at Weight difference at 500°C)/weight of the carbon-based material at 400°C.

According to the carbon-based material of the present invention, preferably, the distribution of nitrogen and oxygen elements and metal elements therein is relatively uniform. For example, in different X-ray micro-areas with the same surface area of the carbon-based material, the coefficient of variation of the content of nitrogen, oxygen and metal elements is less than 20%, more preferably 15% in elemental analysis by X-ray micro-area % or less, particularly preferably 10% or less, more particularly preferably 5% or less. The X-ray micro-area refers to the observation area selected during the elemental analysis of the X-ray micro-area. Among them, the concept of the coefficient of variation refers to the percentage of the standard deviation of a plurality of measured values to their mean, that is, the coefficient of variation CV=(standard deviation SD/mean MN)×100%. Wherein, the method for performing X-ray micro-area elemental analysis can be determined according to conventional methods in the field of instrument analysis, for example, a specific testing method can include: using an energy spectrum analyzer along the length of carbon-based materials in the range of 25-250nm, such as carbon nanomaterials Scan the length direction of the tube to determine the concentration or content of nitrogen atoms, oxygen atoms and metal atoms in the length direction respectively (measure 5 concentrations or contents), and scan five effective samples made of the same nano-carbon material respectively. Electron microscope-energy spectrum analysis, scan 5 different carbon nanotubes for each sample, obtain 25 concentration or content data for nitrogen atom, oxygen atom and metal atom respectively, calculate the variation coefficient of corresponding nitrogen atom, oxygen atom and metal atom . The coefficient of variation here refers to the percentage of the standard deviation of the 25 measured values to their mean, ie, the coefficient of variation CV=(standard deviation SD/mean MN)×100%. In order to better reflect the distribution uniformity of nitrogen, oxygen and metal elements in the carbon-based material, the surface area of the carbon-based material selected in the X-ray micro-area elemental analysis can be 10-250 nm ² , preferably 20-200nm ² .

Wherein, the structural form of the carbon-based material may include at least one of the structural forms of carbon nanotubes, graphene, fullerenes, nano-carbon particles, activated carbon, thin-layer graphite, carbon nanofibers and nanodiamonds.

Wherein, the carbon-based material can be one or more of carbon-based materials with carbon nanotubes, graphene, fullerenes, nano-carbon particles, activated carbon, thin-layer graphite, carbon nanofibers and nano-diamond structures mixture. Wherein, the carbon-based material has a structure selected from carbon nanotubes, graphene, fullerenes, nano-carbon particles, activated carbon, thin-layer graphite, carbon nanofibers and nanodiamonds.

Wherein, preferably, the metal element includes at least one of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium.

The present invention also provides a method for preparing a carbon-based material, which comprises the following steps: (1) mixing a solid carbon source, a precursor and water to obtain a mixed material; wherein, the precursor contains an organic alkali source and inorganic alkali sources, the organic alkali sources include organic amines and/or quaternary ammonium bases; the inorganic alkali sources include hydroxides of metal elements and/or salts of basic metal elements; the metal elements include alkalis at least one of metal elements and/or alkaline earth metal elements; (2) hydrothermal treatment is performed on the mixed material obtained in step (1) to obtain the hydrothermally treated material; and the solids in the hydrothermally treated material are separated; (3) calcining the solid in the hydrothermally treated material obtained in step (2).

According to the method of the present invention, the mixing time and temperature have no special requirements and can be varied within a wide range, for example, the mixing time can be 0.5-72 h, and the mixing temperature can be 20-80°C.

According to the method of the present invention, wherein, the molar ratio of the carbon element in the solid carbon source to the nitrogen element in the organic alkali source can be 1:(0.002-50), preferably 1:(0.005-20), More preferably, it is 1:(0.01-10).

According to the method of the present invention, wherein, the molar ratio of the carbon element in the solid carbon source to the inorganic alkali source can be 1:(0.005-10), preferably 1:(0.008-5), more preferably 1 : (0.01-2).

According to the method of the present invention, wherein, the weight ratio of carbon element to water in the solid carbon source may be 1:(1-100), preferably 1:(5-20).

According to the method of the present invention, particularly preferably, the precursor further contains hydrogen peroxide, and the molar ratio of nitrogen in the organic alkali source to hydrogen peroxide is 1:(0.01-10); more preferably, the The molar ratio of nitrogen element and hydrogen peroxide in the organic alkali source is 1:(0.05-5).

According to the method of the present invention, wherein, the hydrothermal treatment refers to a reaction condition in which part of the water is maintained in a liquid state under autogenous pressure at a temperature above 100° C. under a sealed condition. It is obtained by pressing; preferably, the temperature for hydrothermal treatment is 105-200°C; more preferably, it is 120-180°C. Wherein, the hydrothermal treatment time can be 0.5-96h, preferably 2-72h.

Wherein, the operation of separating solids in the material after hydrothermal treatment can be performed by conventional separation methods such as centrifugation and/or filtration.

Wherein, after separating the solid in the material after hydrothermal treatment, the solid can be dried, and the drying conditions can be changed within a wide range. The present invention does not specifically limit the drying conditions, and can be a conventional choice. Preferably, The drying temperature is 80-180°C, and the time is 0.5-24h. The drying can be carried out under normal pressure or under reduced pressure (ie, negative pressure).

Wherein, the calcination can be performed in an inactive atmosphere, an oxygen-containing atmosphere, or in an inactive atmosphere and an oxygen-containing atmosphere in sequence, wherein the inactive atmosphere refers to the formation of an inactive gas atmosphere, the inert gas such as group zero element gas (eg argon) and/or nitrogen. Preferably, the calcination is performed in an oxygen-containing gas, and the content of oxygen in the oxygen-containing gas is 2-25% by volume based on the total volume of the oxygen-containing gas. In order to carry out the present invention more conveniently and at low cost, preferably, the calcination can be carried out in air.

The conditions for calcination can be varied within a wide range, for example, the calcination temperature is 200-500°C, preferably 300-450°C, and the calcination time is 0.5-48h, preferably 2-24h. For roasting, a temperature-programmed strategy can be used for heating treatment. For example, when the roasting temperature is 200-450 °C, first roast at 200-300 °C for 1-12 hours, and then roast at 310-450 °C for 1-12 hours; When the temperature is 300-450℃, firstly calcinate at 300-350℃ for 1-12h, and then calcinate at 380-450℃ for 1-12h. Among them, after the calcination is completed, the temperature can be naturally cooled to room temperature.

According to the method of the present invention, the choice of the solid carbon source can be a conventional choice in the field of carbon catalysis, as long as the solid carbon source has the catalytic function of catalyzing hydrocarbon oxidation after hydrothermal treatment, for example, the solid carbon source It may include at least one of carbon nanotubes, graphene, fullerenes, nanocarbon particles, activated carbon, thin-layer graphite, carbon nanofibers, nanodiamonds, and the like. Preferably, the solid carbon source includes at least one of carbon nanotubes, nanodiamonds and graphene.

Wherein, the carbon nanotubes may include single-wall carbon nanotubes and/or multi-wall carbon nanotubes. The specific surface area of the carbon nanotubes can vary within a wide range, for example, 20-1000 m ² /g, preferably 30-500 m ² /g. The carbon nanotubes can be obtained commercially or prepared according to literature methods, which are well known to those skilled in the art and will not be repeated here.

According to the method of the present invention, preferably, when the solid carbon source is multi-wall carbon nanotubes, the W ₅₀₀ /W ₈₀₀ of the multi-wall carbon nanotubes can be in the range of 0.02-0.5; The W ₅₀₀ /W ₈₀₀ of the multi-walled carbon nanotubes is in the range of 0.05-0.25. In this preferred case, the carbon-based material obtained by the method of the present invention can obtain better catalytic effect when used as a catalyst, especially when used as a catalyst for the dehydrogenation reaction of hydrocarbon substances, can obtain a higher conversion rate of raw materials and product selectivity. Wherein, W ₈₀₀ refers to the reduction rate of the weight of the solid carbon source at 800°C relative to the weight at 400°C under the condition of air atmosphere and an initial temperature of 25°C and a temperature rise of 10°C/min, namely (the The difference between the weight of the solid carbon source at 400°C and the weight of the solid carbon source at 800°C)/the weight of the solid carbon source at 400°C, W ₅₀₀ refers to the air atmosphere and the initial temperature of 25°C and 10 Under the heating condition of ℃/min, the reduction rate of the weight of the solid carbon source at 500 ℃ relative to the weight at 400 ℃, that is (the weight of the solid carbon source at 400 ℃ and the solid carbon source at Weight difference at 500°C)/weight of the solid carbon source at 400°C.

In a more preferred embodiment of the present invention, the solid carbon source is multi-walled carbon nanotubes, and the specific surface area of the multi-walled carbon nanotubes is 50-500 m ² /g, preferably 100-400 m ² /g; W ₅₀₀ /W ₈₀₀ of the multi-walled carbon nanotubes may be in the range of 0.02-0.5; more preferably, the W ₅₀₀ /W ₈₀₀ of the multi-walled carbon nanotubes may be in the range of 0.05-0.25.

Wherein, the solid carbon source may also contain oxygen element, nitrogen element and other non-metallic elements (such as phosphorus atom and sulfur atom) according to different sources, or may not contain oxygen element, nitrogen element and other non-metallic elements (such as phosphorus atom) and sulfur atoms).

According to the method of the present invention, when the solid carbon source contains oxygen, the content of oxygen is generally not higher than 2% by weight, preferably not higher than 0.5% by weight, more preferably not higher than 0.2% by weight.

According to the method of the present invention, when the solid carbon source contains nitrogen, the nitrogen content is generally not higher than 0.5% by weight, preferably not higher than 0.2% by weight, more preferably not higher than 0.1% by weight.

According to the method of the present invention, when the solid carbon source contains other non-metallic elements (such as phosphorus atoms and sulfur atoms), the solid carbon source contains other non-metallic heteroatoms (such as phosphorus atoms) except for oxygen atoms and nitrogen atoms. and sulfur atoms) in total (in terms of elements) is generally not higher than 0.5% by weight, preferably not higher than 0.2% by weight, more preferably not higher than 0.1% by weight.

According to the method of the present invention, the organic amine may include one or more of aliphatic amines, alcohol amines, amides, alicyclic amines and aromatic amines.

In the present invention, the quaternary ammonium base can be various organic quaternary ammonium bases; the aliphatic amine can be various compounds formed after at least one hydrogen in NH ₃ is replaced by an aliphatic hydrocarbon group (preferably an alkyl group). ; The alcohol amine can be various compounds formed after at least one hydrogen in NH ₃ is replaced by a hydroxyl-containing aliphatic hydrocarbon group (preferably an alkyl group); the amide can be that the hydroxyl group in the carboxylic acid is replaced by an amino group (or an amine The alicyclic amine can be a variety of compounds formed after at least one hydrogen in NH ₃ is replaced by a cycloalkane group; the aromatic amine can be at least one hydrogen in NH ₃ is replaced by an aromatic hydrocarbon group Various compounds formed after substitution.

Specifically, the quaternary ammonium base can be a quaternary ammonium base shown in formula I, the aliphatic amine can be an aliphatic amine represented by formula II, and the alcohol amine can be an alcohol amine represented by formula III:

(Formula I)

In formula I, R ₁ , R ₂ , R ₃ and R ₄ are each a C ₁ -C ₄ alkyl group, and the C ₁ -C ₄ alkyl group includes a C ₁ -C ₄ straight-chain alkyl group and a C ₃ -C ₄ branched alkyl groups, for example: R ₁ , R ₂ , R ₃ and R ₄ can each be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl Butyl.

R ⁵ (NH ₂ ) _n (Formula II)

In formula II, n is an integer of 1 or 2. When n is 1, R ⁵ is a C ₁ -C ₆ alkyl group, including a C ₁ -C ₆ straight chain alkyl group and a C ₃ -C ₆ branched chain alkyl group, such as methyl, ethyl, n-propyl , isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-amyl or n-hexyl. When n is 2, R ⁵ is a C ₁ -C ₆ alkylene group, including a C ₁ -C ₆ straight chain alkylene group and a C ₃ -C ₆ branched chain alkylene group, such as methylene, ethylene , n-propylene, n-butylene, n-pentylene or n-hexylene. More preferably, the aliphatic amine compound is one or more of ethylamine, n-butylamine, butanediamine and hexamethylenediamine.

(HOR ⁶ ) _m NH _(3-m) (Formula III)

In formula III, m R ⁶ are the same or different, and each is a C ₁ -C ₄ alkylene group, including a C ₁ -C ₄ straight chain alkylene group and a C ₃ -C ₄ branched chain alkylene group, such as methylene, ethylene, n-propylene and n-butylene; m is 1, 2 or 3. More preferably, the alcoholamine compound is one or more of monoethanolamine, diethanolamine and triethanolamine.

Wherein, specific examples of the aliphatic amine may include, but are not limited to, at least one of ethylamine, n-propylamine, n-butylamine, di-n-propylamine, butanediamine and hexamethylenediamine. Specific examples of the fatty alcohol amine may include, but are not limited to, at least one of monoethanolamine, diethanolamine, and triethanolamine; specific examples of the quaternary ammonium base may include, but are not limited to, tetramethylammonium hydroxide, tetraethyl At least one of ammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. Specific examples of the amide may include, but are not limited to, at least one of formamide, acetamide, propionamide, butyramide, isobutyramide, acrylamide, polyacrylamide, caprolactam, dimethylformamide, and dimethylacetamide. A sort of. Specific examples of the alicyclic amine may include, but are not limited to, triethylenediamine, diethylenetriamine, hexamethylenetetramine, hexamethyleneimine, triethylenediamine, cycloethyleneimine , at least one of morpholine, piperazine and cyclohexylamine. Specific examples of the aromatic amine may include, but are not limited to, aniline, diphenylamine, benzidine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-toluidine, m-toluidine, p-toluidine, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 2,6-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline At least one of methylaniline, 2,4,6-trimethylaniline, o-ethylaniline, N-butylaniline and 2,6-diethylaniline.

Wherein, examples of the inorganic alkali source may include but are not limited to lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, Lithium Carbonate, Sodium Carbonate, Potassium Carbonate, Rubidium Carbonate, Cesium Carbonate, Calcium Bicarbonate, Calcium Carbonate, Magnesium Bicarbonate, Magnesium Carbonate, Strontium Bicarbonate, Strontium Carbonate, Barium Bicarbonate, Barium Carbonate, Lithium Bicarbonate, Sodium Bicarbonate , at least one of potassium bicarbonate, rubidium bicarbonate and cesium bicarbonate.

On the other hand, the present invention also provides the carbon-based material prepared by the above method.

Wherein, the carbon-based material obtained by this method may contain 60-99% by weight of carbon element, 0.1-16% by weight of nitrogen element, 0.5-20% by weight of oxygen and 0.05-8% by weight of metal element, preferably 80- 98% by weight of carbon element, 0.2-8% by weight of nitrogen element, 1-10% by weight of oxygen element and 0.1-4% by weight of metal element, more preferably 85-95% by weight of carbon element, 0.5-6% by weight of carbon element % nitrogen, 3-8 wt % oxygen and 0.2-3 wt % metal.

Wherein, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the ratio of the amount of oxygen determined by the peak in the range of 533.1-533.5 eV to the amount of oxygen determined by the peak in the range of 531.8-532.2 eV is 1 -10 range.

Among them, in the X-ray photoelectron energy spectrum of the carbon-based material obtained by this method, the amount of oxygen determined by the peak in the range of 529.5-530.8eV accounts for the amount of oxygen determined by the peak in the range of 526.0-535.0eV The ratio is 0.01 -0.1 range.

Wherein, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the ratio of the amount of nitrogen determined by the peak in the range of 398.0-400.5eV to the amount of nitrogen determined by the peak in the range of 395.0-405.0eV is 0.5 -0.85 range.

Wherein, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the ratio of the amount of nitrogen determined by the peak in the range of 400.6-401.5 eV to the amount of nitrogen determined by the peak in the range of 395.0-405.0 eV is 0.15 -0.5 range.

Wherein, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the ratio of the amount of carbon element determined by the peak in the range of 283.8-284.2 eV to the amount of carbon element determined by the peak in the range of 280.0-294.0 eV is 0.6 -1 range.

Among them, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the sum of the amount of carbon element determined by the peak in the range of 286.2-286.6eV and the amount of carbon element determined by the peak in the range of 288.6-289.0eV and 280.0 The ratio of the amount of carbon element determined by the peak in the range of -294.0 eV is in the range of 0.02-0.2.

Among them, in the X-ray photoelectron spectrum of the carbon-based material obtained by this method, the ratio of the amount of carbon element determined by the peak in the range of 286.2-286.6 eV to the amount of carbon element determined by the peak in the range of 288.6-289.0 eV is 0.3 -2 range.

For the carbon-based material obtained by the method of the present invention, W ₅₀₀ /W ₈₀₀ is preferably in the range of 0.02-0.5, more preferably in the range of 0.05-0.25. In this way, better catalytic effect can be obtained, especially when it is used as a catalyst for the dehydrogenation reaction of hydrocarbons, higher conversion rate of feedstock and selectivity of products can be obtained.

The carbon-based material obtained by the method of the present invention has relatively uniform distribution of nitrogen, oxygen and metal elements. For example, in the X-ray micro-area elemental analysis, in different X-ray micro-areas with the same surface area of the carbon-based material, the coefficient of variation of the content of nitrogen, oxygen and metal elements is below 20%. The X-ray micro-area refers to the observation area selected during the elemental analysis of the X-ray micro-area. Among them, the concept of the coefficient of variation refers to the percentage of the standard deviation of a plurality of measured values to their mean, that is, the coefficient of variation CV=(standard deviation SD/mean MN)×100%. Wherein, the method for performing X-ray micro-area elemental analysis can be determined according to conventional methods in the field of instrument analysis, for example, a specific testing method can include: using an energy spectrum analyzer along the length of carbon-based materials in the range of 25-250nm, such as carbon nanomaterials Scan the length direction of the tube to determine the concentration or content of nitrogen atoms, oxygen atoms and metal atoms in the length direction respectively (measure 5 concentrations or contents), and scan five effective samples made of the same nano-carbon material respectively. Electron microscope-energy spectrum analysis, scan 5 different carbon nanotubes for each sample, obtain 25 concentration or content data for nitrogen atom, oxygen atom and metal atom respectively, calculate the variation coefficient of corresponding nitrogen atom, oxygen atom and metal atom . The coefficient of variation here refers to the percentage of the standard deviation of the 25 measured values to their mean, ie, the coefficient of variation CV=(standard deviation SD/mean MN)×100%. In order to better reflect the distribution uniformity of nitrogen, oxygen and metal elements in the carbon-based material, the surface area of the carbon-based material selected in the X-ray micro-area elemental analysis can be 10-250 nm ² , preferably 20-200nm ² .

Among them, the possible reasons why the method of the present invention obtains carbon-based materials with the above-mentioned special characterization parameters include that the method of the present invention combines hydrothermal and roasting processes under specific material types and material ratios.

The structural form of the carbon-based material obtained by the method of the present invention may include at least one of the structural forms of carbon nanotubes, graphene, fullerenes, nano-carbon particles, activated carbon, thin-layer graphite, carbon nanofibers and nanodiamonds.

In yet another aspect, the present invention also provides the use of the carbon-based material as described above in catalyzing hydrocarbon oxidation.

Wherein, the number of carbon atoms of the hydrocarbon may be 2-15, and the hydrocarbon includes at least one of alkane, alkene and aromatic hydrocarbon containing an alkyl group; the alkyl group contains at least two carbon atoms. Preferably, the hydrocarbon includes at least one of butane, 1-butene, ethylbenzene, propane, ethane and pentane.

Among them, the above carbon-based materials can be used as catalysts in hydrocarbon oxidation reactions, and have higher catalytic oxidation performance of hydrocarbons.

Wherein, the conditions of the hydrocarbon oxidation reaction can be the conventional process conditions of the catalytic oxidation reaction of light alkanes, such as the temperature of the reaction can be 200-650 ℃, preferably 300-600 ℃, more preferably 350-550 ℃, still more preferably 400-450℃, the pressure of the reaction can be 0.05-80MPa, preferably 0.1-40MPa, more preferably 0.1-20MPa, still more preferably 0.1-5MPa, the concentration of hydrocarbons can be 1-30% by volume, preferably It is 1-10% by volume, and the molar ratio of hydrocarbon and oxygen can be (0.1-10): 1, preferably (0.2-5): 1. In addition to hydrocarbon and oxygen, the raw material can also contain other substances in the form of carrier gas. The introduced equilibrium gas, wherein the carrier gas may contain at least one of nitrogen, group zero element gas (eg, argon), CO ₂ , water vapor, and the like. The duration of the reaction can be selected according to the temperature of the contact, and the duration of the reaction can be expressed by the volumetric space velocity of the feed gas. Generally, the volumetric space velocity of the feed gas may be 0.1-10000h ^-1 , preferably 1-6000h ^-1 , more preferably 5-5000h ^-1 , further preferably 10-4000h ^-1 .

The present invention is further described in detail below by means of examples. In the following examples and comparative examples, unless otherwise specified, the reagents used are all commercially available analytical reagents. The carbon content of carbon nanotubes without oxygen element is more than 96% by weight, the ash content is less than 1.5% by weight, and the specific surface area is 168 m ² /g, purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences. The carbon nanotube containing oxygen element has a carbon content of more than 95% by weight, an oxygen element content of 1.1% by weight, an ash content of less than 1.2% by weight, and a specific surface area of 211 m ² /g, purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences. The carbon content of graphene is more than 99% by weight, the ash content is less than 0.8% by weight, and the specific surface area is 627 m ² /g, which was purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

In the following examples and comparative examples, X-ray photoelectron spectroscopy analysis was performed on an ESCALab250 X-ray photoelectron spectroscopy instrument of Thermo Scientific Corporation. The excitation source is a monochromatic Al Kα X-ray with an energy of 1486.6 eV and a power of 150 W. The penetration energy used for the narrow scan was 30 eV. The base vacuum for analytical testing was 6.5 x ^10-10 mbar. The electron binding energy was corrected with the C1s peak of elemental carbon (284.0 eV). The relevant data processing is carried out on the ThermoAvantage software that comes with the X-ray photoelectron spectrometer, the version number is V5.926. In the analysis module, the industry-known sensitivity factor method is used for quantitative analysis.

In the following examples and comparative examples, the thermogravimetric analysis was carried out on a TA5000 thermal analyzer, the test conditions were air atmosphere, the heating rate was 10°C/min, and the temperature range was 25°C to 1000°C.

In the following examples and comparative examples, the specific surface area was measured using an ASAP2000 N ₂ physical adsorption instrument from Micromertrics, USA.

In the following examples and comparative examples, a scanning electron microscope (XL 30 ESEM scanning electron microscope from PHILIPS, the Netherlands) equipped with an energy dispersive analyzer (component) was used to determine the nitrogen atoms and oxygen on the surface of carbon nanomaterials (taking carbon nanotubes as an example) The uniformity of the distribution of atoms and metal atoms, the specific test method is: use an energy spectrum analyzer to scan along the length direction of carbon nanotubes with a length in the range of 25-250nm, and determine the nitrogen and oxygen atoms and metal atoms in the Concentration in the length direction (measurement of 5 concentrations), five effective samples made of the same nano-carbon material were subjected to SEM-energy dispersive analysis respectively, each sample was scanned with 5 different carbon nanotubes, nitrogen atoms and 25 concentration data were obtained for oxygen atoms and metal atoms, respectively, and the coefficients of variation of the corresponding nitrogen atoms, oxygen atoms and metal atoms were calculated. The coefficient of variation here refers to the percentage of the standard deviation of the 25 measured values to their mean, ie, the coefficient of variation CV=(standard deviation SD/mean MN)×100%.

Example 1

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursors (tetrapropylammonium hydroxide and sodium hydroxide) and water were stirred and mixed for 2 hours to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in the tetrapropylammonium hydroxide is 1:0.1, the molar ratio of the solid carbon source to the sodium hydroxide is 1:0.5, the solid carbon source The weight ratio to water is 1:10; the mixed materials obtained above are placed in a sealed high-pressure reaction kettle with a polytetrafluoroethylene lining, and hydrothermally treated at 140° C. under autogenous pressure for 24 hours. The solid in the material is separated by filtration and dried, and the drying temperature is 120°C, until the solid obtained by filtration and separation basically maintains a constant weight (drying time is 6h) to obtain the dried material, and then the obtained dried material is The carbon-based material of this example was obtained by calcining in air at a calcination temperature of 330° C. for 2 hours, and then calcined in air at a calcination temperature of 430° C. for 2 hours.

Example 2

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursors (tetramethylammonium hydroxide and potassium hydroxide) and water were stirred and mixed for 1 hour to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in tetramethylammonium hydroxide is 1:0.05, the molar ratio of the solid carbon source to potassium hydroxide is 1:0.01, and the solid carbon source The weight ratio to water is 1:5, and the mixed material obtained above is placed in a sealed high-pressure reaction kettle with a polytetrafluoroethylene lining, and hydrothermally treated at 180° C. under autogenous pressure for 24 hours. The solid in the material is separated by filtration and dried, and the drying temperature is 120°C, until the solid obtained by filtration and separation basically maintains a constant weight (drying time is 6h) to obtain the dried material, and then the obtained dried material is The carbon-based material of this example was obtained by calcining in air at a calcination temperature of 300° C. for 2 hours, and then at a calcination temperature of 400° C. in air for 2 hours.

Example 3

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursor (tetraethylammonium hydroxide and calcium hydroxide) and water are stirred and mixed for 3 hours to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in tetraethylammonium hydroxide is 1:5, the molar ratio of the solid carbon source to calcium hydroxide is 1:2, and the solid carbon source is The weight ratio to water is 1:20; the mixed materials obtained above are placed in a sealed high-pressure reaction kettle with a polytetrafluoroethylene lining, and hydrothermally treated at 120° C. under autogenous pressure for 48 hours. The solid in the material is separated by filtration and dried, and the drying temperature is 120°C, until the solid obtained by filtration and separation basically maintains a constant weight (drying time is 6h) to obtain the dried material, and then the obtained dried material is The carbon-based material of this example was obtained by calcining in air at a calcination temperature of 350° C. for 2 hours, and then calcined in air at a calcination temperature of 450° C. for 2 hours.

Example 4

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursor (tetrapropylammonium hydroxide and sodium hydroxide) and water were stirred and mixed for 5 hours to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in the tetrapropylammonium hydroxide is 1:0.002, the molar ratio of the solid carbon source to the sodium hydroxide is 1:0.005, and the solid carbon source is 1:0.005. The weight ratio to water is 1:2; the mixed materials obtained above are placed in a sealed high-pressure reaction kettle with a polytetrafluoroethylene lining, and hydrothermally treated at 180° C. under autogenous pressure for 12 h. The solid in the material is separated by filtration and dried, and the drying temperature is 120°C, until the solid obtained by filtration and separation basically maintains a constant weight (drying time is 6h) to obtain the dried material, and then the obtained dried material is The carbon-based material of this example was obtained by calcining in air at a calcination temperature of 330° C. for 2 hours, and then calcined in air at a calcination temperature of 380° C. for 2 hours.

Example 5

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursors (tetrapropylammonium hydroxide and sodium hydroxide) and water were stirred and mixed for 6 hours to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in the tetrapropylammonium hydroxide is 1:50, the molar ratio of the solid carbon source to the sodium hydroxide is 1:10, and the solid carbon source The weight ratio to water is 1:100; the mixed materials obtained above are placed in a sealed high-pressure reaction kettle with a polytetrafluoroethylene lining, and hydrothermally treated at 150° C. under autogenous pressure for 24 hours. The solid in the material is separated by filtration and dried, and the drying temperature is 120°C, until the solid obtained by filtration and separation basically maintains a constant weight (drying time is 6h) to obtain the dried material, and then the obtained dried material is The carbon-based material of this example was obtained by calcining in air at a calcination temperature of 350° C. for 2 hours, and then calcined in air at a calcination temperature of 450° C. for 2 hours.

Example 6

The carbon-based material was prepared by the method of Example 1, except that the temperature of the hydrothermal treatment was 105°C.

Example 7

The carbon-based material was prepared by the method of Example 1, except that the temperature of the hydrothermal treatment was 195°C.

Example 8

The carbon-based material was prepared by the method of Example 1, except that tetrapropylammonium hydroxide was replaced by an equal weight mixture of hexanediamine and n-butylamine, and sodium hydroxide was replaced by sodium carbonate.

Example 9

The carbon-based material was prepared by the method of Example 1, except that tetrapropylammonium hydroxide was replaced by an equal weight mixture of diethanolamine and aniline, and sodium hydroxide was replaced by calcium bicarbonate.

Example 10

The carbon-based material was prepared by the method of Example 1, except that the carbon nanotubes were replaced with graphene of equal weight.

Example 11

The carbon-based material was prepared by the method of Example 1, except that the obtained dried material was calcined in air at a calcination temperature of 330° C. for 4 hours.

Example 12

The carbon-based material was prepared by the method of Example 1, except that the obtained dried material was calcined in air at a calcination temperature of 430° C. for 4 hours.

Example 13

The carbon-based material was prepared by the method of Example 1, except that the obtained dried material was calcined in air at a calcination temperature of 500° C. for 1 h.

Example 14

The carbon-based material was prepared by the method of Example 1, except that the obtained dried material was calcined in air at a calcination temperature of 210° C. for 4 hours.

Example 15

The carbon-based material was prepared by the method of Example 1, except that the solid carbon source was carbon nanotubes containing oxygen, and the calcination was carried out in argon.

Example 16

The carbon-based material was prepared by the method of Example 1, except that the solid carbon source was carbon nanotubes containing oxygen, and the calcination was carried out in air.

Example 17

The carbon-based material was prepared by the method of Example 1, except that the calcination was carried out in nitrogen.

Example 18

The carbon-based material was prepared by the method of Example 1, except that the precursor also contained hydrogen peroxide, wherein the molar ratio of tetrapropylammonium hydroxide to hydrogen peroxide was 1:0.1.

Example 19

The carbon-based material was prepared by the method of Example 10, except that the precursor also contained hydrogen peroxide, wherein the molar ratio of tetrapropylammonium hydroxide to hydrogen peroxide was 1:1.

Example 20

The carbon-based material was prepared by the method of Example 15, except that the precursor also contained hydrogen peroxide, wherein the molar ratio of tetrapropylammonium hydroxide to hydrogen peroxide was 1:2.

Comparative Example 1

The solid carbon source (carbon nanotubes without oxygen elements), the precursors (tetrapropyl ammonium hydroxide and sodium hydroxide) and water are mixed for 12 hours at normal temperature and pressure to obtain a mixed material, wherein the solid carbon The molar ratio of carbon in the source to nitrogen in tetrapropylammonium hydroxide is 1:0.1, the molar ratio of the solid carbon source to sodium hydroxide is 1:0.5, the weight of the solid carbon source and water The ratio is 1:10; the mixed materials obtained above are dried, and the drying temperature is 120 ° C until the solid obtained by filtration and separation maintains a substantially constant weight (drying time is 6h) to obtain the dried materials, and then The obtained dried material was calcined in air at a calcination temperature of 330 °C for 2 h, and then calcined in air at a calcination temperature of 430 °C for 2 h, and the calcined material was used as the carbon-based material of this comparative example.

Comparative Example 2

At room temperature (25°C), the solid carbon source (carbon nanotubes without oxygen elements), the precursors (tetrapropylammonium hydroxide and sodium hydroxide) and water were stirred and mixed for 6 hours to obtain a mixed material, wherein, The molar ratio of the carbon element in the solid carbon source to the nitrogen element in the tetrapropylammonium hydroxide is 1:0.1, and the molar ratio of the solid carbon source to the sodium hydroxide is 1:0.5. The resulting material was placed in a sealed autoclave with a polytetrafluoroethylene lining, hydrothermally treated at 140° C. under autogenous pressure for 24 hours, and the solids in the hydrothermally treated material were separated by filtration and dried. The drying temperature was 120° C. until the solid obtained by filtration and separation maintains a substantially constant weight (drying time is 6 h) to obtain a dried material, and then the obtained dried material is used as the carbon-based material of this comparative example.

Test Example 1

Referring to the method in the literature (Jian Zhang et al., Science 322 (2008), 73-77) or the method cited, for the carbon-based materials obtained in Examples 1-20 and Comparative Examples 1-2 and purchased as described above Elemental analysis and XPS analysis of carbon nanotubes with and without oxygen elements. Among them, the X-ray photoelectron spectra were all measured at a temperature of 300 °C in a helium atmosphere for 3 h. The results are shown in Table 1.

In Table 1, O1 in the XPS spectrum column represents the ratio of the amount of oxygen determined by the peak in the range of 533.1-533.5 eV to the amount of oxygen determined by the peak in the range of 531.8-532.2 eV; O2 represents the amount of oxygen determined by the X-ray photoelectron spectrum The ratio of the amount of oxygen element determined by the peak in the range of 529.5-530.8 eV to the amount of oxygen element determined by the peak in the range of 526.0-535.0 eV×100 (percentage value). C1 in the XPS spectrum column represents the ratio of the amount of carbon determined by the peak in the range of 283.8-284.2 eV to the amount of carbon determined by the peak in the range of 280.0-294.0 eV × 100 (percentage value); C2 represents 286.2-286.6 eV The sum of the amount of carbon determined by the peak in the range and the amount of carbon determined by the peak in the range of 288.6-289.0eV and the amount of carbon determined by the peak in the range of 280.0-294.0eV × 100 (percentage value); C3 Refers to the ratio of the amount of carbon element determined by the peak in the range of 286.2-286.6 eV to the amount of carbon element determined by the peak in the range of 288.6-289.0 eV. N1 in the XPS spectrum column refers to the ratio of the amount of nitrogen determined by the peak in the range of 398.0-400.5 eV to the amount of nitrogen determined by the peak in the range of 395.0-405.0 eV × 100 (percentage value); N2 refers to 400.6-401.5 eV The ratio of the amount of nitrogen determined by the peak in the range to the amount of nitrogen determined by the peak in the range of 395.0-405.0 eV×100 (percentage value). W represents W ₅₀₀ /W ₈₀₀ × 100 (percentage value). C, N, O, and M in the elemental composition column represent the elemental composition of carbon, nitrogen, oxygen, and metal, respectively. CV represents the variation coefficient of nitrogen, oxygen and metal elements in different X-ray micro-regions with the same surface area of the carbon-based material during elemental analysis of the X-ray micro-area, where M in the CV column represents the metal element The coefficient of variation of the content.

Table 1

According to the analytical test data of Examples 1-20 and Comparative Examples 1-2 in Table 1, it can be seen that the peaks in the range of 533.1-533.5 eV in the XPS spectrum of carbon-based materials may be determined due to hydrothermal and calcination. The ratio of the amount of oxygen to the amount of oxygen determined by the peak in the range of 531.8-532.2eV is in the range of 1-10; the amount of oxygen determined by the peak in the range of 529.5-530.8eV accounts for 526.0-535.0eV The ratio of the amount of oxygen determined by the peak in the range is in the range of 0.01-0.1; the ratio of the amount of nitrogen determined by the peak in the range of 398.0-400.5eV and the amount of nitrogen determined by the peak in the range of 395.0-405.0eV. The ratio is in the range of 0.5-0.85; the ratio of the amount of nitrogen determined by the peak in the range of 400.6-401.5 eV to the amount of nitrogen determined by the peak in the range of 395.0-405.0 eV is in the range of 0.15-0.5; 283.8- The ratio of the amount of carbon determined by the peak in the range of 284.2eV to the amount of carbon determined by the peak in the range of 280.0-294.0eV is in the range of 0.6-1; the amount of carbon determined by the peak in the range of 286.2-286.6eV The ratio of the amount to the sum of the amount of carbon element determined by the peak in the range of 288.6-289.0eV and the amount of carbon element determined by the peak in the range of 280.0-294.0eV is in the range of 0.02-0.2; The ratio of the amount of carbon element determined by the peak to the amount of carbon element determined by the peak in the range of 288.6-289.0 eV is in the range of 0.3-2; W ₅₀₀ /W ₈₀₀ is 0.02-0.5; different X-ray micro-regions with the same area Among them, the coefficient of variation of the content of nitrogen, oxygen and metal elements is 20% or less.

Test Example 2

0.25g of carbon-based materials obtained in Examples 1-20 and Comparative Examples 1-2 and carbon nanotubes containing oxygen elements and carbon nanotubes without oxygen elements purchased as described above were used as catalysts, and were loaded into a universal fixed bed. In the micro-quartz tube reactor, both ends of the micro-quartz tube reactor are sealed with quartz sand, and under the conditions of normal pressure and 420 ° C, the material (the volume concentration of butane is 1.98%, the molar ratio of butane and oxygen is 2:3, The equilibrium gas is nitrogen) and the total volume space velocity is 1000h ^-1 to carry out the reaction, and after the reaction for 8h, according to the method in the literature (Jian Zhang et al., Science 322 (2008) 73-77), the butane conversion rate, butane di The olefin selectivity and total olefin selectivity are listed in Table 2.

Table 2

According to the data in Table 2, it can be found that the carbon-based material obtained by the present invention can be used as a catalyst to simultaneously improve the selectivity and conversion rate of olefins prepared by oxidative dehydrogenation of hydrocarbons. When the carbon-based material preferably contains 80-98 wt % carbon element, 0.5-8 wt % nitrogen element, 1-10 wt % oxygen element and 0.1-4 wt % metal element, the X-ray photoelectron of the carbon-based material In the energy spectrum, when the ratio of the amount of oxygen element determined by the peak in the range of 533.1-533.5eV to the amount of oxygen element determined by the peak in the range of 531.8-532.2eV is in the range of 1.2-5, it can be further simultaneously improved. Selectivity and Conversion of Oxidative Dehydrogenation of Hydrocarbons to Olefins. In addition, when the hydrothermal treatment temperature is preferably 120-180° C. and the calcination temperature is 300-450° C., the selectivity and conversion rate of olefins prepared by oxidative dehydrogenation can be further simultaneously improved. At the same time, when the precursor contains hydrogen peroxide, the conversion rate and olefin selectivity can be further improved.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner unless they are inconsistent. In order to avoid unnecessary repetition, the present invention provides The combination method will not be specified otherwise.

In addition, the various embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims (22)

1. A carbon-based material, characterized in that: based on the total weight of the carbon-based material, the carbon-based material contains 60-99 wt % carbon element, 0.1-16 wt % nitrogen element, 0.5-20 wt % % of oxygen and 0.05-8% by weight of metal elements; wherein, the metal elements include at least one of alkali metal elements and/or alkaline earth metal elements, and in the X-ray photoelectron spectrum of the carbon-based material, 533.1- The ratio of the amount of oxygen determined by the peak in the range of 533.5eV to the amount of oxygen determined by the peak in the range of 531.8-532.2eV is in the range of 1-10, and the amount of nitrogen determined by the peak in the range of 398.0-400.5eV. The ratio of the amount to the amount of nitrogen element determined by the peak in the range of 395.0-405.0 eV is in the range of 0.5-0.85. 2 . The carbon-based material according to claim 1 , wherein, based on the total weight of the carbon-based material, the carbon-based material contains 80-98 wt % carbon element, 0.2-8 wt % nitrogen element, 1 wt % -10% by weight of oxygen element and 0.1-4% by weight of metal element, in the X-ray photoelectron spectrum of the carbon-based material, the amount of oxygen element determined by the peak in the range of 533.1-533.5eV and the range of 531.8-532.2eV The ratio of the amount of oxygen element determined by the peaks is in the range of 1.2-5. 3. The carbon-based material according to claim 2, wherein the carbon-based material contains 85-95 wt % carbon element, 0.5-6 wt % nitrogen element, 3-8 wt % oxygen element and 0.2-3 wt % % by weight of metal element, in the X-ray photoelectron spectrum of the carbon-based material, the ratio of the amount of oxygen determined by the peak in the range of 533.1-533.5eV to the amount of oxygen determined by the peak in the range of 531.8-532.2eV is in within the range of 1.5-2.5. 4. The carbon-based material according to any one of claims 1-3, wherein, in the X-ray photoelectron spectrum of the carbon-based material, the amount of oxygen element determined by the peak in the range of 529.5-530.8 eV accounts for 526.0- The ratio of the amount of oxygen element determined by the peak in the range of 535.0 eV is in the range of 0.01-0.1. 5. The carbon-based material according to any one of claims 1-3, wherein, in the X-ray photoelectron spectrum of the carbon-based material, the amount of nitrogen determined by a peak in the range of 400.6-401.5 eV is equal to 395.0 The ratio of the amount of nitrogen element determined by the peak in the range of -405.0 eV is in the range of 0.15-0.5. 6. The carbon-based material according to any one of claims 1-3, wherein, in the X-ray photoelectron spectrum of the carbon-based material, the amount of carbon element determined by a peak in the range of 283.8-284.2 eV is the same as 280.0-294.0 The ratio of the amount of carbon determined by the peak in the eV range is in the range of 0.6-1; the ratio of the amount of carbon determined by the peak in the range of 286.2-286.6 eV to the amount of carbon determined by the peak in the range of 288.6-289.0 eV The ratio of the sum to the amount of carbon determined by the peak in the range of 280.0-294.0eV is in the range of 0.02-0.2; the amount of carbon determined by the peak in the range of 286.2-286.6eV and the peak in the range of 288.6-289.0eV The ratio of the amount of carbon element determined is in the range of 0.3-2. 7. The carbon-based material according to any one of claims 1-3, wherein, in different X-ray micro-regions with the same surface area of the carbon-based material, the content of nitrogen element, oxygen element and metal element The coefficients of variation were each below 20%. 8. The carbon-based material according to any one of claims 1-3, wherein W ₅₀₀ /W ₈₀₀ of the carbon-based material is in the range of 0.02-0.5; wherein, W ₈₀₀ refers to air atmosphere and 25 Under the initial temperature of ℃ and the heating condition of 10 ℃/min, the reduction rate of the weight of the carbon-based material at 800 ℃ relative to the weight at 400 ℃, W ₅₀₀ refers to the air atmosphere and the initial temperature of 25 ℃ and 10 Under the temperature rising condition of °C/min, the reduction rate of the weight of the carbon-based material at 500 °C relative to the weight at 400 °C. 9. The carbon-based material according to any one of claims 1-3, wherein the structural morphology of the carbon-based material comprises carbon nanotubes, graphene, fullerenes, nano-carbon particles, activated carbon, thin-layer graphite, At least one of the structural forms of carbon nanofibers and nanodiamonds; the metal element includes at least one of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium. 10. A method for preparing the carbon-based material according to any one of claims 1-9, characterized in that: the method comprises the steps of: (1) mixing solid carbon source, precursor and water to obtain mixed material; wherein, described precursor contains organic alkali source and inorganic alkali source, and described organic alkali source includes organic amine and/or quaternary ammonium alkali; The inorganic alkali source includes hydroxides of metal elements and/or salts of alkaline metal elements; the metal elements include at least one of alkali metal elements and/or alkaline earth metal elements; (2) the mixed material obtained in step (1) is subjected to hydrothermal treatment to obtain the hydrothermally treated material; and the solid in the hydrothermally treated material is separated; (3) calcining the solid in the hydrothermally treated material obtained in step (2). 11. The method according to claim 10, wherein the molar ratio of carbon in the solid carbon source to nitrogen in the organic alkali source is 1:(0.002-50); in the solid carbon source The molar ratio of the carbon element in the solid carbon source to the inorganic alkali source is 1:(0.005-10); the weight ratio of the carbon element in the solid carbon source to the water is 1:(1-100). 12. The method according to claim 10 or 11, wherein the molar ratio of carbon in the solid carbon source to nitrogen in the organic alkali source is 1:(0.01-10); the solid carbon The molar ratio of the carbon element in the source to the inorganic alkali source is 1:(0.01-2); the weight ratio of the carbon element in the solid carbon source to the water is 1:(5-20). 13. The method of claim 10, wherein the precursor further contains hydrogen peroxide, and the molar ratio of nitrogen element to hydrogen peroxide in the organic alkali source is 1:(0.01-10). 14. The method according to claim 10, wherein the temperature for hydrothermal treatment is 105-200°C; the time for hydrothermal treatment is 0.5-96h; the temperature for roasting is 200-500°C, and the time for roasting is 0.5-48h . 15. The method according to claim 14, wherein the temperature for hydrothermal treatment is 120-180°C; the temperature for calcination is 300-450°C. 16. The method of claim 10, wherein the calcination is performed in an oxygen-containing gas, and the oxygen-containing gas has an oxygen content of 2-25 vol% based on the total volume of the oxygen-containing gas. 17. The method of claim 10, wherein the solid carbon source is selected from at least the group consisting of carbon nanotubes, graphene, fullerenes, nanocarbon particles, thin-layer graphite, activated carbon, carbon nanofibers, and nanodiamonds. A sort of. 18. The method of claim 10, wherein the organic amine comprises at least one of aliphatic amine, alcohol amine, amide, alicyclic amine and aromatic amine; the aliphatic amine is selected from ethylamine, normal At least one of propylamine, n-butylamine, di-n-propylamine, butanediamine and hexamethylenediamine; the alcohol amine is selected from at least one of monoethanolamine, diethanolamine and triethanolamine; the quaternary ammonium base is selected from four At least one of methylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide; the amide is selected from formamide, acetamide, propionamide, butyramide, isobutyramide , at least one of acrylamide, polyacrylamide, caprolactam, dimethylformamide and dimethylacetamide; the alicyclic amine is selected from triethylenediamine, diethylenetriamine, hexamethylene At least one of tetramine, hexamethyleneimine, triethylenediamine, cycloethyleneimine, morpholine, piperazine and cyclohexylamine; the aromatic amine is selected from aniline, diphenylamine, benzidine , o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-toluidine, m-toluidine, p-toluidine, 2,3-dimethylaniline, 2,4-dimethylaniline, 2 ,5-dimethylaniline, 2,6-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2,4,6-trimethylaniline, o-ethylaniline , at least one of N-butylaniline and 2,6-diethylaniline; wherein, the inorganic alkali source includes lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, hydrogen Magnesium oxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate and cesium bicarbonate at least one of. 19. The carbon-based material prepared by the method of any one of claims 10-18. 20. Use of the carbon-based material of any one of claims 1-9 and 19 in catalyzing a hydrocarbon oxidation reaction. 21. The use according to claim 20, wherein the number of carbon atoms of the hydrocarbon is 2-15, and the hydrocarbon includes at least one of alkanes, alkenes and aromatic hydrocarbons containing an alkyl group; the alkyl group contains at least two carbon atoms. 22. The use of claim 21, wherein the hydrocarbon comprises at least one of butane, 1-butene, ethylbenzene, propane, ethane, and pentane.