A carbon-coated nickel-gallium catalyst for high-efficiency synthesis of high-carbon alcohol in aqueous-phase coupling and a preparation method and application thereof

Abstract

The application discloses a carbon-coated nickel-gallium catalyst for high-efficiency synthesis of high-carbon alcohol in an ethanol aqueous-phase coupling reaction and a preparation method and application thereof, and belongs to the technical field of catalysts. The method comprises the following steps: adding a nickel salt and malic acid into deionized water and stirring to form a homogeneous solution; adding a gallium salt and titanium dioxide into the homogeneous solution, stirring at room temperature, and drying to obtain a precursor; and calcining the precursor under a nitrogen atmosphere to obtain the carbon-coated nickel-gallium catalyst. The catalyst exhibits excellent catalytic performance in the ethanol aqueous-phase coupling reaction, and the yield of high-carbon alcohol with C4 and above reaches 40.5%, and meanwhile, the organic phase selectivity is kept above 95.5%.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous coupling of ethanol, its preparation method, and its application. Background Technology

[0002] In the field of fine chemicals, higher alcohols with carbon chain lengths of C4-C18 are cornerstone chemicals supporting the industry's development. Their unique amphiphilic molecular structure not only provides a core framework for the molecular design of high-performance surfactants, enabling precise control of the interfacial tension, dispersion stability, and aggregate structure of surfactant systems, but also serves as an environmentally friendly green solvent, widely used in fragrance purification, pharmaceutical intermediate refining, and food additive preparation, efficiently adapting to key unit operations such as extraction, crystallization, and emulsification. Typical examples include hexanol (C6), which serves as a high-quality plasticizer precursor, and heptanol (C7), a core intermediate in the synthesis of high-end fragrances, fully demonstrating the core application value of higher alcohols as multifunctional chemical carriers.

[0003] As the global energy structure accelerates its transition towards renewable energy, bio-based higher alcohols have become a research hotspot in the field of energy materials due to their excellent environmental compatibility and resource renewability. Higher alcohols prepared from renewable biomass such as vegetable oils and sugars through biocatalysis exhibit significant advantages as fuel additives: they can not only increase the cetane number of fuels by ≥15%, significantly optimizing combustion efficiency, but also reduce PM2.5 emissions during combustion by more than 30%. From a life-cycle perspective, these bio-based higher alcohols can achieve carbon neutrality or even negative carbon emissions, becoming a key link between biomass resources and high-end energy materials.

[0004] In the synthesis of higher alcohols, the Guerbet catalytic condensation reaction has always been a research focus due to its excellent atom economy (theoretical atom utilization rate close to 100%). This reaction follows a "three-step cascade catalytic mechanism": First, the alcohol molecule undergoes dehydrogenation under the action of a catalyst to generate an aldehyde intermediate; second, the aldehyde intermediate undergoes Claisen condensation at the basic sites of the catalyst to convert into an α,β-unsaturated aldehyde; third, the unsaturated aldehyde is further hydrogenated to finally generate a saturated higher alcohol. The efficiency of the initial dehydrogenation and final hydrogenation steps directly depends on the electronic structure and electron transfer capability of the catalyst's metal active center, and is the core factor determining the overall reaction efficiency.

[0005] Current mainstream Guerbet reaction catalytic systems mostly rely on platinum group metals such as ruthenium (Ru) and rhodium (Rh). Although they can achieve condensation efficiencies of over 80%, they suffer from two major bottlenecks: First, precious metals are prone to leaching during the reaction, leading to a significant decrease in catalyst cycle stability. After three cycles, the catalytic activity of conventional systems generally declines by more than 40%. Second, platinum group metals are expensive, typically accounting for more than 65% of the total catalyst cost. This high cost barrier severely restricts the large-scale industrial application of this technology.

[0006] Nickel-based catalysts possess significant resource advantages (its content in the Earth's crust reaches 1.3 × 10⁻⁶). 4 With its tunable electronic structure and low ppm (parts per liter), nickel-based catalysts are widely recognized as an ideal alternative to noble metal catalysts. However, the application of nickel-based catalysts in the Guerbet reaction still faces inherent challenges that are difficult to overcome. For example, the carbon-shell coated nickel catalyst (Ni@C) disclosed in Chinese patent CN117138788A is prone to topological defects in the carbon shell when the reaction temperature exceeds 200°C. This causes the nickel grains to lose their stable binding and migrate, agglomerate, and severely sinter, with the nickel grain size increasing sharply from the initial 5 nanometers to 50 nanometers. This structural deterioration further triggers a highly competitive methanation side reaction (methane selectivity of over 60%), ultimately leading to a significant limitation on carbon chain growth efficiency. The yield of C4 and higher carbon alcohols remains below 20%, which is difficult to meet the needs of industrial production. Summary of the Invention

[0007] To address the problem of low C4+ higher alcohol yield (17.9%) when using existing carbon-coated nickel-based catalysts for the synthesis of higher alcohols from aqueous small molecule alcohols, this invention proposes a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols from aqueous ethanol coupling, along with its preparation method and application.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling includes the following steps:

[0010] Add nickel (Ni) salt and malic acid to deionized water and stir to form a homogeneous solution;

[0011] Gallium (Ga) salt and titanium dioxide were added to the homogeneous solution, stirred at room temperature for 1-2 hours, and dried to obtain the precursor.

[0012] The precursor was calcined under a nitrogen atmosphere to obtain a carbon-coated nickel-gallium catalyst (NiGa@C-TiO2).

[0013] This invention constructs a phase-specific titanium dioxide composite support, providing atomic-level anchoring sites and stable interfaces for the active metal phase, effectively inhibiting its ripening and aggregation, and ensuring the long-term stability of the catalyst. The support, with its lattice rigidity and chemical inertness, endows the catalyst with excellent mechanical strength and environmental tolerance. Surface hydroxyl groups optimize the mass transfer process and suppress side reactions by regulating the hydrophilicity-hydrophobicity balance. This interface engineering synergistically promotes hydrogen spillover, lowers the dehydrogenation energy barrier, and achieves selective conversion of the reaction pathway to higher alcohols by reconstructing reactant adsorption behavior, thereby systematically improving product yield.

[0014] Furthermore, the molar ratio of the nickel salt to the gallium salt is (0.5-6):1, preferably 1:1.

[0015] Furthermore, the nickel salt is selected from nickel nitrate or nickel acetate, preferably nickel nitrate.

[0016] Furthermore, the gallium salt is selected from gallium nitrate or gallium acetate, preferably gallium nitrate.

[0017] Furthermore, the titanium dioxide is nano-sized titanium dioxide with a particle size of 100-300 nm.

[0018] Furthermore, the roasting temperature is 450-650℃, preferably 550℃; the roasting time is 1-3 hours, preferably 2 hours.

[0019] The present invention also provides a carbon-coated nickel-gallium catalyst prepared by the above preparation method.

[0020] The present invention also provides the application of the carbon-coated nickel-gallium catalyst in the catalytic synthesis of higher alcohols from ethanol in an aqueous phase.

[0021] This invention also provides a method for the aqueous synthesis of higher alcohols from small molecule alcohols, comprising the following steps: mixing ethanol, water, sodium hydroxide and carbon-coated nickel-gallium catalyst and placing them in a high-pressure reactor, introducing hydrogen to replace the air, reacting at 180°C, initial hydrogen pressure 0.1 MPa and stirring speed 1500 rpm for 12 hours, then raising the temperature to 230°C and reacting for 6 hours, after the reaction is terminated, the mixture spontaneously separates into an oil layer and an water layer, and the oil phase product obtained by centrifugation is the target higher alcohol.

[0022] Furthermore, the small molecule alcohol is ethanol, and the higher alcohol is an alcohol with 4-16 carbon atoms.

[0023] Furthermore, the mass ratio of the ethanol, water, sodium hydroxide, and carbon-coated nickel-gallium catalyst is 5:5:0.88:0.25.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] This invention uses nano-titanium dioxide as a carrier and optimizes the adsorption / desorption balance of reactants on the catalyst surface by controlling the electronic structure of Ni and Ga active centers, thereby effectively controlling the reaction pathway and improving the synthesis efficiency of higher alcohols. Experimental results show that this catalyst exhibits excellent catalytic performance in the aqueous coupling reaction of ethanol, maintaining a high level of yield and selectivity for C4 and above higher alcohols, with a significant yield improvement compared to traditional nickel-based catalysts. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 The images show the XRD patterns of the catalysts prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0028] 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.

[0029] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0032] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0033] This invention provides a method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0034] 1) Preparation of homogeneous solution: Select soluble nickel salt (nickel nitrate or nickel acetate, preferably nickel nitrate) and malic acid, add them to deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0035] 2) Precursor preparation: Add soluble gallium salt (gallium nitrate or gallium acetate, preferably gallium nitrate) and nano-sized titanium dioxide to the above homogeneous solution; control the molar ratio of soluble nickel salt to soluble gallium salt to be (0.5-6):1 (e.g., 0.5:1, 1:1, 2:1, 4:1 or 6:1, preferably 1:1), and stir continuously at room temperature for 1-2 hours (e.g., 1 hour) to ensure that all components are fully mixed; after stirring, dry the mixture to remove moisture and obtain the catalyst precursor;

[0036] 3) Preparation of catalyst by calcination: The dried precursor is calcined under a nitrogen atmosphere; the calcination temperature is controlled at 450-650℃ (e.g., 450℃, 500℃, 550℃, 600℃ or 650℃, preferably 550℃), and the calcination time is 1-3 hours (e.g., 2 hours); after calcination, it is naturally cooled to obtain carbon-coated nickel-gallium catalyst (NiGa@C-TiO2).

[0037] This invention provides a method for the aqueous phase synthesis of higher alcohols from small molecule alcohols, comprising the following steps:

[0038] S1. Reaction system preparation: Ethanol, water, and sodium hydroxide were weighed and mixed with the carbon-coated nickel-gallium catalyst (NiGa@C-TiO2) prepared above according to a mass ratio of 5:5:0.88:0.25. The four substances were mixed evenly and added into the high-pressure reactor as the reaction system.

[0039] S2. Preparation before reaction: Verify the airtightness of the high-pressure reactor to ensure there is no leakage; after the verification is successful, introduce high-purity hydrogen into the reactor to replace the air in the system and eliminate the interference of air on the reaction.

[0040] S3, segmented temperature-controlled reaction:

[0041] First stage reaction: The temperature inside the reactor is raised to 180℃, the initial hydrogen pressure is controlled at 0.1MPa, the stirring rate is 1500rpm, and the reaction is continued for 12 hours under these conditions.

[0042] Second stage reaction: After the first stage reaction is completed, the temperature inside the reactor is raised to 230°C, and the initial hydrogen pressure and stirring rate are kept constant, and the reaction continues for 6 hours.

[0043] Product separation and collection: After the reaction is terminated, the reaction system is allowed to cool naturally to room temperature. The mixture will spontaneously separate into two phases, forming an upper oil layer and a lower water layer. The oil layer and water layer are separated by centrifugation. The resulting oil phase product is the target higher alcohol (an alcohol with a carbon chain length of 4-16 carbon atoms).

[0044] Unless otherwise specified, "room temperature" in this invention refers to 30±2℃.

[0045] All raw materials used in this invention are commercially available. The nano-sized titanium dioxide used in the following embodiments of this invention is specifically: content ≥99%, 100-300nm, hydrophilic, rutile.

[0046] The technical solution of the present invention will be further illustrated by the following embodiments.

[0047] Example 1

[0048] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0049] 1) Add 0.845g of nickel nitrate and 2.563g of malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0050] 2) Add 1.453g of gallium nitrate and 1.468g of nano-sized titanium dioxide to the above homogeneous solution, control the molar ratio of nickel nitrate to gallium nitrate to be 1:1, stir continuously at room temperature for 1 hour, dry, and obtain the precursor.

[0051] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the carbon-coated nickel-gallium catalyst, denoted as Ni1Ga1@C-TiO2.

[0052] Example 2

[0053] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0054] 1) Add 0.428g of nickel nitrate and 2.563g of malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0055] 2) Add 1.975g gallium nitrate and 1.486g nano-sized titanium dioxide to the above homogeneous solution, control the molar ratio of nickel nitrate to gallium nitrate to be 0.5:1, stir continuously at room temperature for 1 hour, dry, and obtain the precursor;

[0056] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the carbon-coated nickel-gallium catalyst, denoted as Ni. 0.5 Ga1@C-TiO2.

[0057] Example 3

[0058] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0059] 1) Add 1.905g of nickel nitrate and 2.563g of malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution.

[0060] 2) Add 1.066g gallium nitrate and 1.486g nano-sized titanium dioxide to the above homogeneous solution, control the molar ratio of nickel nitrate to gallium nitrate to be 2:1, stir continuously at room temperature for 1 hour, dry, and obtain the precursor;

[0061] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the carbon-coated nickel-gallium catalyst, denoted as Ni2Ga1@C-TiO2.

[0062] Example 4

[0063] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0064] 1) Add 2.420g of nickel nitrate and 2.563g of malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0065] 2) Add 0.617g gallium nitrate and 1.486g nano-sized titanium dioxide to the above homogeneous solution, control the molar ratio of nickel nitrate to gallium nitrate to be 4:1, stir continuously at room temperature for 1 hour, dry, and obtain the precursor;

[0066] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the carbon-coated nickel-gallium catalyst, denoted as Ni4Ga1@C-TiO2.

[0067] Example 5

[0068] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0069] 1) Add 2.628g of nickel nitrate and 2.563g of malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0070] 2) Add 0.417g gallium nitrate and 1.486g nano-sized titanium dioxide to the above homogeneous solution, control the molar ratio of nickel nitrate to gallium nitrate to be 6:1, stir continuously at room temperature for 1 hour, dry, and obtain the precursor.

[0071] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the carbon-coated nickel-gallium catalyst, denoted as Ni6Ga1@C-TiO2.

[0072] Example 6

[0073] Same as Example 1, except that in step 3), the calcination temperature is 450°C.

[0074] Example 7

[0075] Same as Example 1, except that in step 3), the calcination temperature is 500°C.

[0076] Example 8

[0077] Same as Example 1, except that in step 3), the calcination temperature is 600°C.

[0078] Example 9

[0079] Same as Example 1, except that in step 3), the calcination temperature is 650°C.

[0080] Comparative Example 1

[0081] Same as Example 1, except that in step 2), no nano-sized titanium dioxide is added, and the resulting catalyst is denoted as Ni1Ga1@C.

[0082] Comparative Example 2

[0083] Same as Example 1, except that gallium nitrate is not added in step 2), and the resulting catalyst is denoted as Ni@C-TiO2.

[0084] Comparative Example 3

[0085] A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous ethanol coupling, comprising the following steps:

[0086] 1) Add 3.389g gallium nitrate and 2.563g malic acid to 60mL of deionized water, and stir to completely dissolve the solids to form a homogeneous and stable solution;

[0087] 2) Add 1.486 g of nano-sized titanium dioxide to the above homogeneous solution, stir continuously at room temperature for 1 hour, and dry to obtain the precursor;

[0088] 3) The precursor was calcined at 550°C for 2 hours under a nitrogen atmosphere and then naturally cooled to obtain the catalyst, denoted as Ga@C-TiO2.

[0089] Application Example 1

[0090] The catalysts prepared in Examples 1-9 and Comparative Examples 1-3 were added to a 70 mL high-pressure reactor to co-catalyze the carbon-carbon coupling reaction of ethanol with a homogeneous base to produce higher alcohols. Specifically, 5 g of ethanol, 5 g of water, 0.88 g of sodium hydroxide, and 0.25 g of catalyst were mixed as the reaction system and placed in the high-pressure reactor. After verification of the seal, high-purity hydrogen was introduced to replace the air in the reaction system. The reaction was then carried out at 180 °C, an initial hydrogen pressure of 0.1 MPa, and a stirring rate of 1500 rpm for 12 hours. After the reaction was completed, the system was heated to 230 °C and maintained at this temperature for 6 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the gas phase was collected using a gas bag. The liquid phase product was removed from the reactor and separated into liquid and solid phase catalysts by centrifugation and filtration. The liquid phase naturally separated into oil and water phases after standing. The gas phase products, aqueous phase, and oil phase were all qualitatively and quantitatively analyzed by gas chromatography. The results showed that the main product in the oil phase was C4+ higher alcohols, and the analysis indicated that C4+ higher alcohols were mainly composed of alcohols with 4-16 carbon atoms. The analytical results are shown in Table 1.

[0091] Table 1

[0092] Ethanol conversion rate (C-mol%) Organic phase product yield (C-mol%) C4+ higher alcohol selectivity in liquid products (%) C4+ higher alcohol yield (C-mol%) Example 1 83.8 55.6 95.5 40.5 Example 2 77.3 51.2 92.2 24.7 Example 3 80.2 48.6 92.2 31.2 Example 4 77.4 45.6 90.5 27.7 Example 5 77.2 41.9 84.5 20.5 Example 6 78.6 49.9 94.5 38.7 Example 7 79.7 50.1 92.2 39.9 Example 8 85.5 52.2 91.8 32.2 Example 9 88.6 51.9 89.9 28.5 Comparative Example 1 49.9 26.5 88.5 19.9 Comparative Example 2 56.5 37.8 86.8 24.5 Comparative Example 3 43.2 29.9 76.0 17.9

[0093] As shown in Table 1, the carbon-coated nickel-gallium catalysts prepared in Examples 1-9 by changing the ratio of soluble nickel salt and soluble gallium salt and the carbonization temperature are highly efficient for the synthesis of higher alcohols and can be used for the carbon-carbon coupling of ethanol to higher alcohols. Among them, the catalyst prepared in Example 1 has the best performance, with relatively high levels of ethanol conversion, organic phase product yield, selectivity of liquid phase product C4+ higher alcohol, and yield of C4+ higher alcohol. Compared with the support-modified system, Comparative Example 1 without titanium dioxide support lacks effective structural support and dispersion medium, resulting in the aggregation of active components nickel and gallium in the carbon matrix. This leads to significant disadvantages in key performance indicators such as C4+ higher alcohol yield, ethanol conversion, and organic phase yield. Compared with the bimetallic catalyst system, the C4+ higher alcohol selectivity and yield of the single-metal catalyst systems in Comparative Examples 2 and 3 are significantly reduced, indicating that the bimetallic catalyst system is superior to the single-metal catalyst system in catalyzing the synthesis of higher alcohols from aqueous ethanol.

[0094] Figure 1 The images show the XRD patterns of the carbon-coated nickel-gallium catalyst prepared in Example 1 and the catalyst prepared in Comparative Example 1. Figure 1 As can be seen from the above, the carbon-coated nickel-gallium catalyst of Example 1 has obvious titanium dioxide diffraction peaks with sharp peak shapes, while the peak intensity of elemental Ni is small and wide. This indicates that the active components nickel and gallium on the carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols prepared in Example 1 are successfully loaded on TiO2 and have good dispersion. In contrast, the catalyst prepared in Comparative Example 1 does not have titanium dioxide diffraction peaks, but the elemental Ni peak shape is sharp and has good crystallinity.

[0095] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a carbon-coated nickel-gallium catalyst for the efficient synthesis of higher alcohols via aqueous-phase coupling of ethanol, characterized in that, Includes the following steps: Add nickel salt and malic acid to water and stir to form a homogeneous solution; Gallium salt and titanium dioxide were added to the homogeneous solution, stirred at room temperature, and dried to obtain the precursor. The precursor was calcined under a nitrogen atmosphere to obtain a carbon-coated nickel-gallium catalyst. The molar ratio of the nickel salt to the gallium salt is (0.5-6):1; The titanium dioxide is hydrophilic rutile titanium dioxide with a particle size of 100-300 nm; The roasting temperature is 450-650℃, and the time is 1-3 hours.

2. The preparation method according to claim 1, characterized in that, The nickel salt is selected from nickel nitrate or nickel acetate.

3. The preparation method according to claim 1, characterized in that, The gallium salt is selected from gallium nitrate or gallium acetate.

4. A carbon-coated nickel-gallium catalyst prepared by the preparation method according to any one of claims 1-3.

5. The application of the carbon-coated nickel-gallium catalyst as described in claim 4 in the catalytic aqueous-phase synthesis of higher alcohols from ethanol.

6. A method for synthesizing higher alcohols from ethanol in an aqueous phase, characterized in that, Includes the following steps: Ethanol, water, sodium hydroxide and the carbon-coated nickel-gallium catalyst of claim 4 were mixed and placed in a high-pressure reactor. Hydrogen was introduced to replace the air, and the reaction was carried out at 180°C, initial hydrogen pressure of 0.1 MPa and stirring speed of 1500 rpm for 12 hours. Then the temperature was raised to 230°C and the reaction was carried out for 6 hours. After the reaction was completed, the oil phase was separated to obtain higher alcohols.

7. The method according to claim 6, characterized in that, The mass ratio of ethanol, water, sodium hydroxide, and carbon-coated nickel-gallium catalyst is 5:5:0.88:0.25.

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