Ordered mesoporous carbon nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses an ordered mesoporous carbon nano-catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The preparation method comprises the following steps: by taking gallic acid as a carbon precursor, uniformly dispersing the gallic acid, a template agent and Ni metal salt under the assistance of ultrasonic waves to obtain a prefabricated solution, and then sequentially carrying out solvent evaporation self-assembly and carbonization forming processes to obtain the Ni-coated OMC catalyst. According to the invention, the active metal Ni is highly dispersed and embedded into the ordered mesoporous structure by using a self-assembly method, and the ordered mesoporous confinement structure improves the dispersibility of the catalytic active center of the metal Ni and the stability of the structure and activity of the metal Ni in a hydrothermal environment. The high-dispersion Ni-coated OMC nano-catalyst is further applied to the catalytic process of ethanol water-phase coupling quality-improving synthesis of high-carbon alcohol, and the catalyst has good hydrothermal stability and is easy to separate and recover.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to an ordered mesoporous carbon nanocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon materials are widely used by humans in life and production. Ordered mesoporous carbon (OMC) is a kind of porous carbon material. Due to its uniform mesoporous structure, high specific surface area, large porosity, and inert surface, it has attracted more and more attention in application fields such as energy storage, separation, and catalysis.

[0003] There are mainly two synthesis methods for ordered mesoporous carbon: the hard template method and the soft template method. The hard template method is one of the earliest methods used to prepare ordered mesoporous carbon materials. Common organic carbon sources such as sucrose, phenolic resin, and furfuryl alcohol are filled in an ordered silica template, and an ordered mesoporous structure is obtained after carbonization and etching. However, the etching process often requires corrosive and toxic reagents such as HF, NH 4 、NaOH, etc. In addition, in most of the processes for preparing ordered mesoporous carbon by the soft template method, a crosslinking agent needs to be added additionally to complete the crosslinking process. The crosslinking agents involve toxic carcinogens such as formaldehyde and glyoxal, which are likely to cause adverse effects on the environment, increase the cost of material preparation, and affect the purity of ordered mesoporous carbon. Although the soft template method has improved the preparation efficiency of ordered mesoporous carbon to a certain extent, the industrial development of this method is still limited by the use of harmful and carcinogenic substances such as phenol and formaldehyde in the preparation process. Therefore, exploring green and sustainable carbon precursors for synthesizing mesoporous carbon materials is an important direction.

[0004] In the field of catalytic preparation, when using ordered mesoporous carbon as a carrier, an active metal is usually incorporated by a two-step method, that is, first, ordered mesoporous carbon is prepared, and then the active metal is incorporated by an impregnation method or a co-precipitation method. The impregnation method includes steps such as impregnation, calcination, and activation. This method has a complex process and there will be a problem of metal leaching during the catalytic reaction, while the co-precipitation method also requires a complex operation procedure. In both methods, the doped active metal components are usually deposited on the surface of the carbon carrier, resulting in agglomeration of metal particles during heat treatment and catalytic reaction, thereby affecting the catalytic activity and stability.

[0005] In addition, due to their weak molecular polarity, lipophilicity, high calorific value and other characteristics, higher alcohols (alcohols with 6 or more carbon atoms) are widely used in the synthesis of surfactants, detergents, plasticizers, fuels and other various oxygen-containing fine chemical products, and are very important platform compounds. At the same time, higher alcohols with 8 or more carbon atoms are ideal precursors for aviation fuels, and aviation fuels can be prepared by just one-step reaction of hydrodeoxygenation. The non-precious metal Ni has unique hydrogen transfer properties. Ni sites can promote ethanol dehydrogenation and hydrogen transfer, and the released hydrogen overflows onto the catalyst to promote in-situ hydrogenation of reaction intermediates. Therefore, many scholars are concerned with the development of Ni-based metal catalysts. However, there is currently no nano-catalyst that combines Ni metal and ordered mesoporous carbon to be stable and efficient for catalyzing the synthesis of higher alcohols from aqueous ethanol.

[0006] In summary, there is an urgent need to provide an ordered mesoporous carbon nano-catalyst and its preparation method that are simple and easy to operate, green and environmentally friendly, and can effectively improve the catalytic efficiency and catalytic stability of dehydrogenation-hydrogenation catalysts. Summary of the Invention

[0007] In view of the above technical problems, the present invention proposes an ordered mesoporous carbon nano-catalyst, its preparation method and application. That is, the present invention adopts an ultrasonic-assisted method and a synthetic route of solvent evaporation self-assembly-carbonization molding, specifically: using gallic acid as a carbon precursor, the template agent Pluronic F-127, and Ni metal salt are uniformly dispersed by ultrasonic assistance to obtain a prefabricated solution, and then the precursor is obtained by solvent evaporation self-assembly method, and further dried and carbonized in an inert atmosphere to obtain a highly dispersed Ni@OMC catalyst. The catalyst obtained by the above method has excellent hydrothermal stability, and the specific mechanism involved is: the present invention uses the self-assembly method to highly disperse and embed the active metal Ni into the ordered mesoporous structure. Among them, the ordered mesoporous confinement structure can improve the dispersion of metal catalytic active centers and the stability of their structure and activity in the hydrothermal environment. Utilizing the good hydrothermal stability and easy separation and recovery characteristics of the above catalyst, the highly dispersed Ni@OMC nano-catalyst can be applied to the catalytic process of upgrading aqueous ethanol coupling to synthesize higher alcohols.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] One of the technical solutions of the present invention:

[0010] A preparation method of an ordered mesoporous carbon nano-catalyst, comprising the following steps:

[0011] Using gallic acid as a carbon precursor, uniformly dispersing it with a template agent and Ni metal salt in absolute ethanol by ultrasonic assistance to obtain a prefabricated solution; then successively carrying out solvent evaporation self-assembly and carbonization molding processes to obtain a Ni@OMC catalyst.

[0012] Beneficial effects: Gallic acid (3,4,5-trihydroxybenzoic acid), a polyphenol widely present in various plants in nature in the form of tannic acid, has good environmental degradation characteristics. Biomass gallic acid, as a natural renewable resource, is rich in sources and relatively low in price, and is an environmentally friendly material that fully meets the requirements of green chemistry. Gallic acid has its potential advantages compared with other hydroxyl-containing compounds. For example, the molecular structure of gallic acid contains multiple active functional groups such as hydroxyl groups and carboxyl groups, and the molecular size and shape are moderate. These functional groups can interact with other substances during the synthesis process, such as forming non-covalent bond interactions such as hydrogen bonds and ionic bonds with template agents or cross-linking agents, which is conducive to the formation of an ordered structure during the synthesis process. This interaction can help the gallic acid molecules to be arranged orderly under the guidance of the template, and through a relatively mild carbonization process, the structure of ordered mesoporous carbon is finally formed.

[0013] In summary, based on the strong coordination effect between multivalent metal ions and hydroxyl groups in polyphenol compounds, the present invention uses an ultrasonic-assisted method and a synthetic route of solvent evaporation self-assembly-carbonization molding to prepare Ni-based ordered mesoporous carbon nanomaterials (Ni@OMC). Gallic acid is used instead of traditional phenolic compounds as the carbon precursor, and metal ions Ni 2+ are used instead of carcinogenic formaldehyde or other aldehydes as cross-linking agents. During the synthesis process, Ni 2+ forms a coordination bond with the hydroxyl groups in gallic acid molecules, and cross-links to obtain a micelle composite material composed of gallic acid and F127. Then, the Ni@OMC catalyst obtained through the solvent evaporation self-assembly and carbonization molding process can highly disperse and embed the active metal Ni into the ordered mesoporous structure, thereby improving the dispersion of metal catalytic active centers and the stability of their structure and activity in the hydrothermal environment.

[0014] Optionally, the template agent is Pluronic F-127, with an average molecular weight of 12,000-15,000; the molecular weight is preferably 12,800.

[0015] Optionally, the Ni metal salt is selected from at least one of nickel nitrate hexahydrate, nickel chloride, nickel sulfate, nickel acetate or nickel acetylacetonate; preferably nickel nitrate hexahydrate.

[0016] Optionally, based on gallic acid, the molar ratio of Ni atoms in the Ni metal salt to the gallic acid is 1:(1-3), preferably 1:3.

[0017] Optionally, the ultrasonic power in the ultrasonic-assisted process is 20 kHz.

[0018] Optionally, the carbonization conditions in the carbonization forming process are: carbonizing for 2 h under an inert atmosphere at a carbonization temperature of 500 - 800 °C, preferably at a carbonization temperature of 600 °C.

[0019] Furthermore, the inert atmosphere is at least one of nitrogen, helium, and argon.

[0020] Optionally, the preparation method of the ordered mesoporous carbon nanocatalyst specifically includes the following steps:

[0021] S1: Dissolve the template agent Pluronic F - 127 in absolute ethanol by ultrasonic - assisted method to obtain an F127 absolute ethanol solution;

[0022] S2: Dissolve the carbon source gallic acid and Ni metal salt in absolute ethanol respectively to form uniform sols, slowly add the above two uniform sols into the F127 absolute ethanol solution, and then stir vigorously to obtain a pre - prepared solution;

[0023] S3: Pour the pre - prepared solution in S2 into a polytetrafluoroethylene evaporating dish, dry it at room temperature to constant weight, and slowly volatilize the solvent for self - assembly;

[0024] S4: Subject the gel obtained by drying in S3 to secondary drying and carbonization treatment in sequence to obtain a Ni@OMC nanocatalyst.

[0025] Furthermore, the rotation speed during the vigorous stirring process is 100 - 800 rpm, preferably 600 rpm.

[0026] Furthermore, the temperature of the secondary drying is 50 - 150 °C, preferably 100 °C.

[0027] The second technical solution of the present invention:

[0028] An ordered mesoporous carbon nanocatalyst is prepared by using the above - mentioned preparation method.

[0029] The third technical solution of the present invention:

[0030] The application of the above - mentioned ordered mesoporous carbon nanocatalyst in the field of catalyzing the synthesis of higher alcohols from aqueous ethanol.

[0031] Beneficial effects: Based on the Ni - based catalyst, using ordered mesoporous carbon as a carrier in the present invention can change the dispersion of nickel, exposing more active sites; the long - range ordered pores of mesoporous carbon play a spatial confinement role, preventing the infinite aggregation and swelling of metals, and at the same time avoiding the loss and aggregation of metal active centers in a high - temperature and high - pressure hydrothermal environment; through the confinement effect, the catalytic performance of ethanol coupling reaction is improved. However, the ordered mesoporous carbon structure does not directly affect the catalytic activity of nickel, that is, the catalytic active sites of this catalyst for aqueous - phase reactions are only provided by Ni.

[0032] Optionally, in the process of catalytically synthesizing higher alcohols from aqueous ethanol, by mass ratio, the ordered mesoporous carbon nanocatalyst: inorganic base (sodium hydroxide): ethanol: water = 0.3: 0.88: 5: 5.

[0033] Optionally, the catalytic temperature in the catalytic synthesis of higher alcohols from aqueous ethanol is 160 - 250 °C, preferably 230 °C.

[0034] Beneficial effects: The ordered mesoporous carbon nanocatalyst prepared by the present invention is used to catalyze the carbon-carbon coupling of small molecule alcohol aqueous solution, and higher alcohols can be directly prepared. The reaction conditions are mild and pollution-free, spontaneous phase separation can be achieved, and the selectivity of the higher alcohol product is effectively improved.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] The present invention provides a method for preparing an efficient nickel-based ordered mesoporous carbon nanocatalyst by solvent evaporation self-assembly, and its special application in the catalytic synthesis of higher alcohols in aqueous phase. Among them, the preparation method of the catalyst disclosed by the present invention is convenient and green. The catalyst has excellent hydrothermal stability, and the ordered mesoporous carbon structure enables the active metal Ni to have excellent dispersion, thereby improving the exposure of the metal catalytic active center sites and the stability of their structures and activities in the hydrothermal environment. Further applying the highly dispersed Ni@OMC nanocatalyst to the upgrading synthesis of higher alcohols by ethanol aqueous phase coupling shows excellent selectivity for higher alcohols and hydrothermal stability, and is easy to separate and recycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0038] Figure 1 TEM images of Ni@OMC catalysts prepared with different Ni / GA ratios in Example 1; among them, (a) Ni@OMC-1:15; (b) Ni@OMC-1:7; (c) Ni@OMC-1:3; (d) Ni@OMC-1:2; (e) Ni@OMC-1:1;

[0039] Figure 2 XRD patterns of Ni@OMC catalysts prepared with different Ni / GA ratios in Example 1;

[0040] Figure 3 XRD patterns of Ni@OMC catalysts prepared at different carbonization temperatures in Example 2;

[0041] Figure 4TEM images of Ni@OMC catalysts prepared at different carbonization temperatures in Example 2; where (a) Ni@OMC-400; (b) Ni@OMC-500; (c) and (d) are Ni@OMC-600 at different scales; (e) Ni@OMC-700; (f) Ni@OMC-800. Detailed Description of the Invention

[0042] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0044] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes methods and materials in some alternative embodiments, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0045] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are only exemplary.

[0046] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0047] The embodiments of the present invention disclose a preparation method of an ordered mesoporous carbon nanocatalyst and its application in the aqueous-phase catalytic synthesis of higher alcohols. This catalyst can effectively improve the catalytic efficiency and catalytic stability of dehydrogenation-hydrogenation catalysts and can be used to catalytically synthesize higher alcohol fuel chemicals from aqueous ethanol solutions.

[0048] The above preparation method of the ordered mesoporous carbon nanocatalyst includes the following steps:

[0049] S1: Add the template agent Pluronic F-127 into absolute ethanol and dissolve it by ultrasonic-assisted method to obtain F-127 absolute ethanol solution;

[0050] S2: Dissolve the carbon source gallic acid and Ni metal salt in absolute ethanol solution respectively to form a homogeneous sol, slowly add the sol into the solution in S1, and stir vigorously to obtain a prefabricated solution;

[0051] S3: Pour the prefabricated solution in S2 into a polytetrafluoroethylene evaporating dish for drying, and slowly volatilize the solvent for self-assembly;

[0052] S4: Finally, perform secondary drying and carbonization treatment on the dried gel to obtain Ni@OMC nanocatalyst.

[0053] In the present invention, as a non-precious metal element, metal Ni is quite abundant in the earth's crust and is one of the best noble metal substitution materials. And the present invention uses a self-assembly method to highly disperse the active metal Ni into an ordered mesoporous structure, and this ordered mesoporous confinement structure can improve the dispersion of the metal catalytic active center and the stability of its structure and activity in a hydrothermal environment.

[0054] In some alternative embodiments, the Ni metal salt is selected from at least one of nickel nitrate, nickel chloride, nickel sulfate, nickel acetate or nickel acetylacetonate, and preferably nickel nitrate.

[0055] In some alternative embodiments, the template agent is Pluronic F-127 with an average molecular weight of 12,000 - 15,000; the molecular weight is preferably 12,800.

[0056] In some alternative embodiments, the molar ratio of the Ni metal salt to the carbon source gallic acid is 1:(1 - 15), preferably 1:(1 - 3), and more preferably 1:3.

[0057] In some alternative embodiments, the rotation speed of vigorous stirring in the process of S2 is 100 - 800 rpm, preferably 600 rpm.

[0058] In some alternative embodiments, the temperature of secondary drying in S4 is 50 - 150 °C, preferably 100 °C.

[0059] In some alternative embodiments, the carbonization process in S4 is high-temperature pyrolysis self-reduction in an inert atmosphere. Here, the inert atmosphere is one or more of nitrogen, helium and argon, preferably nitrogen; the carbonization temperature is 400 - 800 °C, preferably 500 - 800 °C, and more preferably 600 °C.

[0060] In addition, the embodiments of the present invention also disclose an ordered mesoporous carbon nanocatalyst prepared by the above preparation method and its application in the catalytic synthesis of higher alcohols.

[0061] The carbon nanocatalyst prepared in the embodiments of the present invention has an ordered mesoporous confinement structure, which shows high activity, high selectivity for long carbon chains, excellent catalytic efficiency and hydrothermal stability in the reaction of ethanol aqueous phase coupling to prepare higher alcohols, and has the advantages of easy separation and recovery, and less pollution.

[0062] In the present invention, "room temperature" refers to 20 - 30 °C unless otherwise specified.

[0063] All raw materials used in the present invention are obtained by purchasing in the market.

[0064] The technical solutions of the present invention will be further described below through examples.

[0065] Example 1 (Setting different molar ratios of Ni and GA)

[0066] A preparation method of an ordered mesoporous carbon nanocatalyst includes the following steps:

[0067] S1: Add 1 g of template Pluronic F-127 (average molecular weight of 12,800) to 20 mL of absolute ethanol, and dissolve it by ultrasonic-assisted method to obtain an F-127 absolute ethanol solution;

[0068] S2: Dissolve 1 g of carbon source gallic acid (GA) and X g (where X represents a variable) of nickel nitrate hexahydrate in 20 mL of absolute ethanol respectively to form a uniform sol. Slowly add the gallic acid absolute ethanol sol and the nickel nitrate hexahydrate absolute ethanol sol to the solution in S1, and stir vigorously (rotation speed is 600 rpm) to obtain a prefabricated solution;

[0069] S3: Pour the prefabricated solution in S2 into a polytetrafluoroethylene evaporating dish for drying (the drying temperature is room temperature, and the drying time is 12 h), and slowly volatilize the solvent for self-assembly;

[0070] S4: Finally, dry the obtained gel at 100 °C for 12 h; perform carbonization treatment at 600 °C in a nitrogen atmosphere for 2 h to obtain the Ni@OMC nanocatalyst;

[0071] Among them, in step S2, the amount of carbon source gallic acid (GA) is controlled to be unchanged, and the loading amount of metal Ni is changed to change the ratio of Ni to GA. For example, the molar ratios of Ni and GA are respectively: 1:1, 1:2, 1:3, 1:7, 1:15; the obtained catalysts are respectively denoted as Ni@OMC-1:1, Ni@OMC-1:2, Ni@OMC-1:3, Ni@OMC-1:7, Ni@OMC-1:15.

[0072] Figure 1 TEM images of Ni@OMC catalysts prepared with different Ni / GA ratios in Example 1. It can be clearly seen from the images that the carbon layer has a wrapped structure, and the nickel metal particles are dispersed in the form of nanoscale particles. As the Ni / GA ratio increases, the amount of metallic Ni in the field of view increases continuously. When Ni∶GA = 1∶3, a regular ordered mesoporous structure is observed.

[0073] Figure 2 XRD patterns of Ni@OMC catalysts prepared with different Ni / GA ratios in Example 1. It can be seen from the patterns that although the amount of Ni loaded in the Ni@OMC catalysts increases, the half-peak intensity of the characteristic diffraction peaks corresponding to metallic Ni remains basically unchanged, indicating that the metal particles do not agglomerate significantly. This is also proved by the TEM images, showing that they have a high degree of dispersion.

[0074] Application Example 1

[0075] Ni@OMC with different Ni / GA ratios synthesized was used in the catalytic process of upgrading ethanol in aqueous phase to synthesize higher alcohols. The specific catalytic conditions are as follows: catalyst mass∶NaOH inorganic base mass∶ethanol∶water = 0.3∶0.88∶5∶5. The temperature of the catalytic process is 230 °C, and the catalytic time is 12 h. The catalytic performance data of Ni@OMC catalysts with different Ni loadings for the catalytic coupling of ethanol in aqueous phase to synthesize higher alcohols are summarized in Table 1. It can be seen from Table 1 that when there is no ordered mesoporous structure, as the metal loading increases, the conversion rate of ethanol increases and the selectivity of isomeric alcohols increases; when the ordered mesoporous carbon structure appears at Ni∶GA = 1∶3, the conversion rate of ethanol is the highest.

[0076] Table 1 Summary of ethanol coupling reaction data of Ni@OMC catalysts prepared with different Ni / GA ratios in Example 1

[0077]

[0078] The calculation formulas for the corresponding data in Table 1 and the following Table 2 are as follows:

[0079] (1)

[0080] (2)

[0081] (3)

[0082] Among them, higher alcohols are alcohols with carbon numbers above 6.

[0083] Example 2 (Setting different carbonization temperatures)

[0084] The difference from Example 1 is that the molar ratio of Ni and GA in step S2 is controlled to be 1:3; the carbonization temperatures in step S4 are changed to 400 °C, 500 °C, 600 °C, 700 °C and 800 °C respectively. The obtained catalysts are denoted as Ni@OMC-400, Ni@OMC-500, Ni@OMC-600, Ni@OMC-700, and Ni@OMC-800 respectively.

[0085] Figure 3 XRD patterns of Ni@OMC catalysts prepared at different carbonization temperatures in Example 2. The main diffraction peaks of the catalysts are metallic Ni, and the main exposed crystal planes are 111, 200, and 220. It can be seen from the figure that when the carbonization temperature is 400 °C, the characteristic peaks of metallic Ni do not appear. As the carbonization temperature increases, the half-peak intensity of the characteristic diffraction peaks of metallic Ni gradually increases, and the crystal grains gradually increase.

[0086] Figure 4 TEM images of Ni@OMC catalysts prepared at different carbonization temperatures in Example 2. At 400 °C, the formation of metal particles was not observed, but as the carbonization temperature increased, the metal crystal grains gradually increased, which was consistent with the XRD test results.

[0087] Application Example 2

[0088] The conditions for catalytic upgrading of ethanol in aqueous phase to synthesize higher alcohols are the same as those in Application Example 1, except that the catalyst used is the one prepared in Example 2. The catalytic performance data for catalytic coupling of ethanol in aqueous phase to synthesize higher alcohols are summarized in Table 2. It can be seen from this that, keeping the metal loading unchanged, as the calcination temperature increases, the conversion rate of Ni@OMC-catalyzed ethanol increases, and the selectivity of isomeric alcohols increases; at 400 °C, the active site metal Ni was not in-situ reduced, resulting in low catalytic activity. When the temperature reached 600 °C, the ethanol conversion rate was the highest; if the carbonization temperature continued to increase, the ethanol conversion rate decreased, and the selectivity of isomeric alcohols decreased.

[0089] Table 2 Summary of ethanol coupling reaction data of Ni@OMC catalysts prepared at different carbonization temperatures in Example 2

[0090]

[0091] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing an ordered mesoporous carbon nanocatalyst, characterized in that: The following steps are involved: Gallic acid is used as a carbon precursor, and is uniformly dispersed in anhydrous ethanol with the assistance of ultrasound with a template and a Ni metal salt, and mixed to obtain a prefabricated solution; then, solvent evaporation self-assembly and carbonization molding processes are sequentially performed to obtain a Ni@OMC catalyst, namely the ordered mesoporous carbon nanocatalyst.

2. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 1, characterized in that: The template agent is Pluronic F-127, and the average molecular weight is 12000-15000.

3. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 1, characterized in that: The Ni metal salt is selected from at least one of nickel nitrate hexahydrate, nickel chloride, nickel sulfate, nickel acetate or nickel acetylacetonate.

4. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 1, characterized in that: Calculated on the basis of gallic acid, the molar ratio of Ni atoms in the Ni metal salt to the gallic acid is 1:(1-3).

5. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 1, characterized in that: The carbonization conditions in the carbonization molding process are: carbonization for 2 hours in an inert atmosphere at a carbonization temperature of 500-800°C.

6. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 1, characterized in that: The method for preparing the ordered mesoporous carbon nanocatalyst specifically comprises the following steps: S1: dissolving the template in anhydrous ethanol by an ultrasonic-assisted method to obtain an anhydrous ethanol solution of the template; S2: Dissolving gallic acid and Ni metal salt in anhydrous ethanol respectively to form a uniform sol, slowly adding the two uniform sols to the template anhydrous ethanol solution, and then vigorously stirring to obtain a prefabricated solution; S3: pouring the prefabricated solution in S2 into a polytetrafluoroethylene evaporating dish for drying, so that the solvent evaporates slowly for self-assembly; S4: The gel obtained by drying in S3 is subjected to secondary drying and carbonization treatment in sequence to obtain a Ni@OMC nanocatalyst.

7. The method for preparing an ordered mesoporous carbon nanocatalyst according to claim 6, characterized in that: The rotation speed during the vigorous stirring process is 100-800 rpm; and / or The secondary drying temperature is 50-150°C.

8. An ordered mesoporous carbon nanocatalyst, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the ordered mesoporous carbon nanocatalyst as claimed in claim 8 in the field of catalyzing the synthesis of higher alcohols from aqueous phase ethanol.

10. The use according to claim 9, characterized in that: In the process of catalyzing the synthesis of higher alcohols from aqueous ethanol, the mass ratio of the ordered mesoporous carbon nanocatalyst: inorganic base: ethanol: water is 0.3: 0.88: 5: 5; and / or The catalytic temperature is 160-250°C.

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