Copper-based catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysis, and particularly provides a copper-based catalyst and a preparation method and application thereof. The preparation method of the copper-based catalyst comprises the following steps: mixing a copper salt, a doped metal salt and an auxiliary agent, and uniformly grinding to obtain a ground product; and carrying out microwave treatment on the ground product to obtain the copper-based catalyst. According to the method, the copper-based catalyst can be rapidly prepared through microwave assistance, the prepared copper-based catalyst can efficiently catalyze hydrodeoxygenation of the oxygen-containing organic matter, and the high target product yield can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysis, and in particular relates to a copper-based catalyst and a preparation method and application thereof. Background Art

[0002] As environmental and energy issues become increasingly prominent, the development of renewable resources has become a key path to solving energy shortages and environmental pollution problems. Among the many renewable resources, biomass resources, as the only renewable organic carbon carrier in nature, can be converted into various fuels and high-value-added chemicals. Biomass resources have the advantages of wide availability, abundant reserves, and low prices, making them an important way to achieve high-value utilization of all biomass components. Taking vanillin, a lignin derivative, as an example, vanillin can be converted into 2-methoxy-4-methylphenol through catalytic hydrodeoxygenation. The hydrodeoxygenation reaction (HDO) of vanillin is often used as a model reaction for studying the catalytic transformation mechanism of biomass due to its challenges in deoxygenation activity and product selectivity. It has important guiding significance for studying downstream reactions of biomass and the efficient utilization of biomass resources.

[0003] Despite the promising prospects for catalytic conversion of biomass resources, its development remains limited by catalysts. Traditional metal catalysts (such as Ni and Pt-based catalysts) exhibit high activity in reactions such as the hydrodeoxygenation of vanillin. However, these reactions require high temperatures and pressures, which can lead to deactivation of these catalysts due to sintering or carbon deposition of metal particles, making it difficult to obtain high yields of the target product. On the other hand, traditional methods for preparing catalysts, including impregnation, co-precipitation, hydrothermal, and sol-gel methods, generally suffer from low efficiency, high raw material costs, low environmental friendliness, and poor catalytic performance. While the impregnation method is simple to operate, it suffers from uneven distribution of active components and prominent metal migration and agglomeration issues. The co-precipitation method allows for controlled component deposition through pH regulation, but the extensive use of precipitants such as ammonia and carbonates leads to the discharge of nitrogen- and salt-containing wastewater, significantly increasing environmental treatment costs. Catalysts prepared by the sol-gel method, while possessing a homogeneous structure, suffer from poor reproducibility due to factors such as the difficulty in controlling the hydrolysis rate of the precursor. While the hydrothermal method can synthesize catalysts with a narrow metal particle size distribution gradient and difficult-to-grain metal particles, the preparation of catalysts by the hydrothermal method is time-consuming and requires a long reaction time. These issues directly increase catalyst manufacturing costs and severely restrict the application and development of catalytic conversion of biomass resources. Summary of the Invention

[0004] To address the aforementioned issues in the prior art, the present invention provides a copper-based catalyst, its preparation method, and its application. The present invention rapidly prepares the copper-based catalyst using microwave assistance. The prepared copper-based catalyst exhibits high catalytic activity in catalytic hydrodeoxygenation reactions and achieves a high yield of the target product.

[0005] In a first aspect, the present invention provides a method for preparing a copper-based catalyst, the preparation method comprising:

[0006] (1) mixing copper salt, doping metal salt and auxiliary agent and grinding them uniformly to obtain a grinding product; wherein,

[0007] The doping metal in the doping metal salt is M, M represents a lanthanide metal, and the auxiliary agent is an organic acid and / or a polyol;

[0008] (2) subjecting the ground product to microwave treatment to form a copper-based oxide doped with M, thereby obtaining a copper-based catalyst.

[0009] The method of the present invention uses microwaves to assist in the thermal conversion of the ground product. The microwave treatment promotes the efficient and synchronous heating of the molecules within the material, significantly shortening the catalyst preparation time. Compared with traditional methods for preparing catalysts, the method of the present invention reduces energy waste and has environmental advantages. In addition, copper salts and doped metal salts form lanthanide metal (M)-doped copper-based oxides after microwave heating. The auxiliary agent can decompose during microwave treatment to produce gaseous products, improving the pore structure of the catalyst. The prepared copper-based catalyst exhibits high catalytic activity and selectivity for the target product.

[0010] In some embodiments of the present invention, the copper salt is copper nitrate, which can improve the uniformity of distribution of each group in the ground product.

[0011] In some embodiments of the present invention, M is selected from La, Ce, Pr, Nd, Sm or Gd. In this case, the prepared copper-based catalyst can improve the yield of the target product while maintaining a high catalytic activity.

[0012] In some embodiments of the present invention, the doping metal salt is a nitrate of a lanthanide metal.

[0013] In some embodiments of the present invention, the molar ratio of the doping metal salt to the copper salt is (0.005-0.2): 1. Preferably, the molar ratio of the doping metal salt to the copper salt is (0.01-0.2): 1.

[0014] In some embodiments of the present invention, the molar ratio of the auxiliary agent to the total amount of the copper salt and the doping metal salt is (0.1-0.4):1.

[0015] In some embodiments of the present invention, the auxiliary agent is an organic acid and / or polyol.

[0016] Preferably, the auxiliary agent is selected from at least one of ascorbic acid, citric acid, malic acid and xylitol. In this case, the prepared copper-based catalyst can have both high catalytic activity and selectivity for the target product.

[0017] In some embodiments of the present invention, the power of the microwave treatment is 400-800 W, and the treatment time is 30-300 s.

[0018] In a second aspect, the present invention provides a copper-based catalyst prepared by the preparation method described in the first aspect of the present invention.

[0019] The present invention uses microwave treatment to grind the product of copper salt, doped metal salt and auxiliary agent to prepare copper-based catalyst, which is lanthanide metal-doped copper oxide (M-CuO x The copper oxide in this catalyst provides active sites, while the doped lanthanide metal (M) modulates the electronic structure of copper, promoting the adsorption of reactants and electron transfer. Furthermore, the lanthanide metal and copper oxide form a stable heterogeneous interface, which not only stabilizes the active site structure but also promotes the efficient hydrodeoxygenation reaction through synergistic acid-base sites.

[0020] In a third aspect, the present invention provides use of the copper-based catalyst described in the second aspect of the present invention in catalyzing the hydrodeoxygenation reaction of oxygen-containing organic matter.

[0021] In some embodiments of the present invention, the oxygen-containing organic matter is selected from biomass compounds. Further, the biomass compound is selected from at least one of vanillin, o-vanillin, ethyl vanillin, cinnamaldehyde, benzaldehyde, 5-hydroxymethylfurfural, methyl levulinate, and ethyl levulinate.

[0022] In some embodiments of the present invention, the application includes: conducting a hydrodeoxygenation reaction of the oxygen-containing organic matter in the presence of the copper-based catalyst in the presence of an alcohol solvent. The alcohol solvent not only serves as a solvent to dissolve the reactants and disperse the catalyst, but also serves as a hydrogen source for transfer hydrogenation. Compared to using hydrogen gas as a hydrogen source, this improves reaction safety and reduces production costs.

[0023] Preferably, the alcohol solvent is at least one of methanol, ethanol, n-propanol, isopropanol and isobutanol. In this case, the conversion rate of the reactants and the yield of the target product can be further improved.

[0024] In some embodiments of the present invention, the alcohol solvent is used in an amount such that the concentration of the oxygen-containing organic matter in the alcohol solvent is 5 to 50 g / L.

[0025] In some embodiments of the present invention, the mass ratio of the copper-based catalyst to the oxygen-containing organic matter is (0.5-0.8) : 1. In this way, the conversion rate is improved while the possibility of side reactions is reduced.

[0026] In some embodiments of the present invention, the hydrodeoxygenation reaction is carried out under stirring conditions, the reaction temperature is 180-220° C., the reaction time is 0.5-8 h, and the stirring speed is 500-800 rpm.

[0027] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 X-ray diffraction patterns of the catalysts prepared in Example 1 and Comparative Example 3;

[0029] Figure 2 This is the gas chromatography detection result spectrum of the reaction product of Application Example 1. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0031] The "ranges" disclosed herein are defined in terms of lower and / or upper limits, with a given range being defined by selecting a lower limit and / or an upper limit. Ranges defined in this manner may be inclusive or exclusive of the end values ​​and may be combined arbitrarily, i.e., any lower limit may be combined with any upper limit to form an unspecified range, and any lower limit may be combined with any other lower limit to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value may itself be combined as a lower limit or upper limit with any other point or single value, or with other lower limits or upper limits to form an unspecified range.

[0032] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0033] In the present invention, the term "metal salt" should be broadly understood to include both anhydrous salts and hydrates thereof. For example, "copper nitrate" may include anhydrous copper nitrate (Cu(NO3)2) and copper nitrate hydrates (e.g., Cu(NO3)2·3H2O, Cu(NO3)2·6H2O).

[0034] A first aspect of the present invention provides a method for preparing a copper-based catalyst, comprising the following steps:

[0035] (1) mixing a copper salt, a doping metal salt, and an auxiliary agent and grinding them uniformly to obtain a ground product; wherein the doping metal in the doping metal salt is M, M represents a lanthanide metal, and the auxiliary agent is an organic acid and / or a polyol;

[0036] (2) subjecting the ground product to microwave treatment to form a copper-based oxide doped with M, thereby obtaining a copper-based catalyst.

[0037] The preparation method of the present invention does not use solvents; instead, the copper-based catalyst can be produced simply by mixing, grinding, and microwave-treating the various materials. This method is simple and easily scalable, significantly shortening the catalyst preparation cycle. Furthermore, the method eliminates the need for chemical reagents such as acids, bases, and organic solvents, making it more economical and environmentally friendly.

[0038] In the present invention, as a copper precursor, the copper salt can be selected from various metal salts containing the elements Cu and O that can undergo a conversion reaction to form copper oxide during the preparation process. In order to promote uniform dispersion of the components in the ground product, the copper salt is preferably copper nitrate.

[0039] In some embodiments, the lanthanide metal (M) is selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), or gadolinium (Gd). In this way, the prepared copper-based catalyst can maintain high catalytic activity while improving selectivity for the target product.

[0040] In the present invention, the doping metal salt is a lanthanide metal salt. According to some embodiments, the doping metal salt is a nitrate of a lanthanide metal. As some preferred examples, the doping metal salt is selected from one or more of lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, and gadolinium nitrate.

[0041] In step (1), the amount of the doping metal salt can be selected according to the amount of the copper salt. According to some embodiments, the molar ratio of the doping metal salt to the copper salt can be (0.005-0.2): 1, for example, 0.005: 1, 0.01: 1, 0.02: 1, 0.025: 1, 0.03: 1, 0.08: 1, 0.1: 1, 0.15: 1, 0.18: 1, 0.2: 1, etc. Preferably, the molar ratio of the doping metal salt to the copper salt is (0.01-0.2): 1. More preferably, the molar ratio of the doping metal salt to the copper salt is (0.02-0.1): 1. In this case, while making the copper-based catalyst have a higher catalytic activity, it can reduce the active sites that may be covered, the structural stability is reduced, and the side reactions are increased due to excessive doping.

[0042] In the present invention, the additive is an organic acid and / or a polyol. During microwave treatment, the additive decomposes to generate gas, thereby regulating the catalyst pore structure. Furthermore, during catalyst preparation, the additive forms a coordination complex with copper ions, promoting more uniform dispersion of the metal ions and improving the copper-based catalyst's ability to adsorb and activate reactants. Preferably, the organic acid is selected from at least one of ascorbic acid, citric acid, and malic acid, and the polyol is xylitol.

[0043] In step (1), the amount of the auxiliary agent can be selected according to the amount of the metal salt. According to some embodiments, the molar ratio of the auxiliary agent to the total amount of the copper salt and the doping metal salt is (0.1-0.4):1, for example, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.36:1, 0.4:1, etc.

[0044] In the present invention, the grinding can be performed in an agate mortar, for example. In addition, the grinding can be performed at room temperature, and the grinding time can be 3 to 10 minutes, for example, 5 minutes, 8 minutes, etc.

[0045] In the present invention, microwave treatment can achieve rapid and uniform heating of the ground product, greatly shortening the preparation time of the catalyst. According to some embodiments, the power of the microwave treatment is 400 to 800 W, for example, 400 W, 500 W, 600 W, 700 W, 800 W, etc. In order to uniformly heat the ground product while avoiding the metal agglomeration and particle size increase that may be caused by excessively long microwave treatment time, which leads to a decrease in catalytic activity, the microwave treatment time is preferably 30 to 300 s, for example, 30 s, 50 s, 60 s, 70 s, 90 s, 100 s, 105 s, 120 s, 150 s, 200 s, 230 s, 270 s, 300 s, etc. In addition, the microwave treatment can be carried out in a microwave oven, for example.

[0046] In the present invention, in order to obtain a powdered copper-based catalyst, the preparation method preferably further comprises: (3) grinding the product obtained in step (2).

[0047] A second aspect of the present invention provides a copper-based catalyst prepared by the preparation method described in the first aspect of the present invention. The copper-based catalyst prepared by the present invention effectively catalyzes the hydrodeoxygenation of oxygen-containing organic matter through the interaction between the lanthanide metal and the copper oxide. In particular, the copper-based catalyst exhibits a highly efficient catalytic effect on the hydrodeoxygenation conversion of biomass compounds under mild conditions (temperature range of 180-220°C).

[0048] To this end, the third aspect of the present invention provides use of the copper-based catalyst described in the second aspect of the present invention in the hydrodeoxygenation reaction of oxygen-containing organic matter.

[0049] In the present invention, the oxygen-containing organic compound can be selected from biomass compounds. It is understood that the biomass compound refers to a biomass compound having oxygen-containing groups. For example, the biomass compound can be one or more of biomass aldehydes / alcohols and biomass esters. "Biomass aldehydes / alcohols" refer to biomass compounds that include aldehyde groups and / or hydroxyl groups in their molecular structure.

[0050] In some embodiments, the biomass compound is at least one of vanillin (VAN), o-vanillin, ethyl vanillin, cinnamaldehyde, benzaldehyde, 5-hydroxymethylfurfural, methyl levulinate and ethyl levulinate, preferably at least one of vanillin, o-vanillin, ethyl vanillin and 5-hydroxymethylfurfural.

[0051] In some embodiments, the application includes: conducting a hydrodeoxygenation reaction of the oxygen-containing organic compound in the presence of an alcoholic solvent in the presence of the copper-based catalyst. The alcoholic solvent, as a reactive solvent, can provide the required hydrogen source during the reaction. To further improve the conversion rate and yield of the target product, the alcoholic solvent is preferably at least one of methanol, ethanol, n-propanol, isopropanol, and isobutanol. More preferably, the alcoholic solvent is isopropanol and / or isobutanol.

[0052] In some embodiments, the amount of the alcohol solvent used is such that the concentration of the oxygen-containing organic matter in the alcohol solvent is 5 to 50 g / L, for example, 5 g / L, 10 g / L, 15 g / L, 18 g / L, 20 g / L, 22 g / L, 30 g / L, 40 g / L, 42 g / L, 45 g / L, 50 g / L, etc.

[0053] In some embodiments, the mass ratio of the copper-based catalyst to the oxygen-containing organic matter is (0.5-0.8):1, for example, 0.5:1, 0.6:1, 0.62:1, 0.65:1, 0.67:1, 0.7:1, 0.75:1, 0.78:1, 0.8:1, etc.

[0054] In some embodiments, the hydrodeoxygenation reaction is carried out under stirring conditions, and the temperature of the hydrodeoxygenation reaction can be 180-220°C, for example, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, etc.; the reaction time can be 0.5-8h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 4h, 5h, 6h, 6.5h, 7h, 8h, etc.; the stirring speed can be 500-800rpm, for example, 550rpm, 600rpm, 650rpm, 700rpm, 800rpm, etc.

[0055] According to some specific embodiments, the application process may include: adding a biomass compound and an alcohol solvent to a reactor (e.g., an autoclave), stirring until the biomass compound is dissolved, then adding a copper-based catalyst, then sealing the reactor, and heating the reactor to 180-220°C under vigorous stirring (500-800 rpm) and stirring the reaction at this temperature for 0.5-8 hours. After the reaction is completed, cooling to room temperature to obtain a mixed solution containing a reaction product. Optionally, the application process further includes: after the reaction is completed, performing solid-liquid separation (e.g., centrifugal separation) on the mixed solution to recover the catalyst therein.

[0056] As some preferred examples, the biomass compound is vanillin. The application includes: hydrodeoxygenating vanillin in an alcohol solvent in the presence of a copper-based catalyst to produce a mixture containing 2-methoxy-4-methylphenol (target product, MMP) and optionally vanillyl alcohol (byproduct, HMP). Additionally, the route for synthesizing the product from the hydrodeoxygenation reaction of vanillin is shown below.

[0057]

[0058] The following embodiments of the present invention are described. The following embodiments are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0059] Examples 1 to 16 are used to illustrate the copper-based catalyst and its preparation method of the present invention.

[0060] Example 1

[0061] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at 800 W for 30 s to form praseodymium-doped copper oxide (2.5% Pr-CuO X Finally, the product was ground evenly to obtain a powdered copper-based catalyst, which was designated as Cat-1.

[0062] Example 2

[0063] Copper salt (copper nitrate, 10 mmol), doping metal salt (lanthanum nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at 800 W for 30 s to form lanthanum-doped copper oxide (2.5% La-CuO X Finally, the product was ground evenly to obtain a powdered copper-based catalyst, which was designated as Cat-2.

[0064] Example 3

[0065] Copper salt (copper nitrate, 10 mmol), doping metal salt (cerium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at a power of 800 W for 30 s to form cerium-doped copper oxide (2.5% Ce-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-3.

[0066] Example 4

[0067] Copper salt (copper nitrate, 10 mmol), doping metal salt (neodymium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at a power of 800 W for 30 s to form neodymium-doped copper oxide (2.5% Nd-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-4.

[0068] Example 5

[0069] Copper salt (copper nitrate, 10 mmol), doping metal salt (samarium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at a power of 800 W for 30 s to form samarium-doped copper oxide (2.5% Sm-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-5.

[0070] Example 6

[0071] Copper salt (copper nitrate, 10 mmol), doping metal salt (gadolinium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at a power of 800 W for 30 s to form gadolinium-doped copper oxide (2.5% Gd-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-6.

[0072] Comparative Example 1

[0073] The copper-based catalyst was prepared according to the method of Example 1, except that praseodymium nitrate was replaced by cobalt nitrate to form cobalt-doped copper oxide (2.5% Co-CuO X ). This catalyst was recorded as Cat-D1.

[0074] Comparative Example 2

[0075] A copper-based catalyst was prepared according to the method of Example 1, except that praseodymium nitrate was replaced by aluminum nitrate to form aluminum-doped copper oxide (2.5% Al-CuO X ). This catalyst was recorded as Cat-D2.

[0076] Example 7

[0077] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (citric acid, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 30 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-7.

[0078] Example 8

[0079] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (malic acid, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 30 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-8.

[0080] Example 9

[0081] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (xylitol, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 30 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-9.

[0082] Example 10

[0083] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (ascorbic acid, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 400 W for 60 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-10.

[0084] Example 11

[0085] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (ascorbic acid, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 600 W for 60 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-11.

[0086] Example 12

[0087] A copper salt (copper nitrate, 10 mmol), a doping metal salt (praseodymium nitrate, 0.25 mmol), and an additive (ascorbic acid, 2.05 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 60 seconds to form praseodymium-doped copper oxide. The product was then ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-12.

[0088] Comparative Example 3

[0089] Copper salt (copper nitrate, 10 mmol) and an auxiliary agent (ascorbic acid, 2 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 30 seconds to form copper oxide (CuOx). Finally, the product was ground to obtain a powdered copper-based catalyst. This catalyst was designated Cat-D3.

[0090] Figure 1Figure 2 is the X-ray diffraction pattern of catalyst Cat-1 and catalyst Cat-D3, wherein the diffraction peaks at 2θ=32.49°, 35.46°, 38.68°, 48.72°, 53.45°, 58.33°, 61.53°, 65.78°, 67.94°, 72.42° and 75.02° correspond to (-110) of the standard CuO card (PDF#45-0937), respectively. The diffraction peak intensities at the (002), (111), (-202), (020), (202), (-113), (022), (113), (311), and (004) crystal planes, especially those at (002) and (111), are significantly higher than those at the other crystal planes. Furthermore, the diffraction peaks of catalysts Cat-1 (2.5% Pr-CuOx) and Cat-D3 (CuOx) match those of a standard CuO card. Further comparison of Cat-1 and Cat-D3 reveals that Pr doping does not change the crystal form of Cat-D3, and no Pr-related diffraction peaks are observed in the figure. It is speculated that the Pr in Cat-1 may exist in a dispersed and amorphous form.

[0091] Comparative Example 4

[0092] A copper salt (copper nitrate, 10 mmol) and a doping metal salt (praseodymium nitrate, 0.25 mmol) were mixed and ground in an agate mortar to obtain a ground product. The ground product was microwaved at 800 W for 30 seconds to form praseodymium-doped copper oxide. Finally, the product was ground to obtain a powdered copper-based catalyst, designated Cat-D4.

[0093] Example 13

[0094] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 0.05 mmol) and additive c (ascorbic acid, 2.01 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at 800 W for 30 s to form praseodymium-doped copper oxide (0.5% Pr-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-13.

[0095] Example 14

[0096] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 0.1 mmol) and auxiliary agent (ascorbic acid, 2.02 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at 800 W for 30 s to form praseodymium-doped copper oxide (1% Pr-CuO X), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-14.

[0097] Example 15

[0098] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 1 mmol) and auxiliary agent (ascorbic acid, 2.2 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at a power of 800 W for 30 s to form praseodymium-doped copper oxide (10% Pr-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-15.

[0099] Example 16

[0100] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 2 mmol) and auxiliary agent (ascorbic acid, 2.4 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a microwave oven and microwaved at 800 W for 30 s to form praseodymium-doped copper oxide (20% Pr-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-16.

[0101] Comparative Example 5

[0102] Copper salt (copper nitrate, 10 mmol), doping metal salt (praseodymium nitrate, 0.25 mmol) and auxiliary agent (ascorbic acid, 2.05 mmol) were mixed and ground evenly in an agate mortar to obtain a ground product. The ground product was placed in a muffle furnace and calcined at 300 ° C for 2 h to obtain praseodymium-doped copper oxide (2.5% Pr-CuO X ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-D5.

[0103] Comparative Example 6

[0104] Copper salt (copper nitrate, 10 mmol) and doped metal salt (praseodymium nitrate, 0.25 mmol) were dissolved in 100 mL of deionized water to obtain a metal salt solution. 100 mL of alkaline solution containing NaOH (10 mmol) and Na2CO3 (20 mmol) was added to the metal salt solution and stirred at room temperature for 3 h to form a solid-liquid mixture containing a precipitate. The mixture was centrifuged to remove the liquid phase, and the centrifuged product was washed 5 times with deionized water until the washing liquid was neutral. The washed product was then dried at 60 ° C for 8 h to obtain a catalyst precursor. The catalyst precursor was then calcined in a muffle furnace at 300 ° C for 2 h to obtain praseodymium-doped copper oxide (2.5% Pr-CuOX ), and finally the product was ground uniformly to obtain a powdered copper-based catalyst. This catalyst was designated as Cat-D6.

[0105] The following application examples 1 to 23 and application comparative examples 1 to 8 are used to illustrate the application of the copper-based catalysts prepared in the above examples and comparative examples in the hydrodeoxygenation reaction of biomass compounds.

[0106] The reaction products were quantitatively analyzed using an Agilent 7820 gas chromatograph (FID detector; HP-5 capillary (30 m × 0.32 nm × 0.25 μm)). The operating conditions were as follows: nitrogen carrier gas at a flow rate of 1.0 mL / min, an inlet temperature of 250°C, and a detector temperature of 300°C. The column oven program was as follows: initial temperature of 80°C, hold for 2 min, then increase to 200°C at a rate of 10°C / min. The injection parameters were split mode with a split ratio of 10:1 and an injection volume of 1 μL. Sample preparation: The mixture was diluted with solvent to an appropriate multiple (within the linear range) and filtered. The resulting liquid phase was analyzed by gas chromatography.

[0107] The conversion rate of the reactants and the yield of each product were calculated according to the following formula:

[0108]

[0109] Application Example 1

[0110] This application example uses vanillin as an example to illustrate the hydrodeoxygenation reaction of biomass compounds.

[0111] 0.3 g of vanillin and 30 mL of methanol were added to a 100 mL high-temperature autoclave and stirred until the vanillin dissolved. 0.2 g of the catalyst Cat-1 prepared in Example 1 was then added. The autoclave was then sealed and heated to 200°C with vigorous stirring (600 rpm). The reaction was allowed to proceed at this temperature for 2 h. After the reaction was complete, the mixture was cooled to room temperature to obtain a mixed solution containing the reaction product. The reaction test results are listed in Table 1.

[0112] Figure 2 This is the gas chromatographic analysis graph corresponding to Application Example 1; the unseparated peak appearing at the abscissa (min) less than 2 corresponds to the solvent peak (the additional 1.581 and 1.742 are intended to explain the numbers on the separation peak line, that is, the position of the unseparated peak appears at 1.581-1.742), the high-intensity characteristic peak appearing at 7.155 corresponds to the target product MMP, the low-intensity characteristic peak appearing at 10.242 corresponds to the substrate VAN, the low-intensity characteristic peak appearing at 11.021 represents the by-product HMP, and the low-intensity characteristic peak appearing at 11.882 may represent an etherification by-product.

[0113] It can be seen that the catalyst Cat-1 successfully catalyzed the hydrodeoxygenation conversion of vanillin, and the catalyst had high selectivity for the target product MMP.

[0114] Application Examples 2 to 16

[0115] Vanillin hydrodeoxygenation was carried out according to the method of Application Example 1, except that the catalysts were replaced with catalysts Cat-1 to Cat-16 prepared in Examples 2 to 16, respectively. The resulting mixture was analyzed by gas chromatography, and the test results are listed in Table 1.

[0116] Comparative Application Examples 1 to 6

[0117] Vanillin hydrodeoxygenation was carried out according to the method of Application Example 1, except that the catalysts were replaced with the catalysts Cat-D1 to Cat-D6 prepared in Comparative Examples 1 to 6, respectively. The reaction solution was analyzed by gas chromatography, and the test results are listed in Table 1.

[0118] Table 1

[0119]

[0120]

[0121] 1: “M / Cu” represents the molar ratio of the doping metal salt to the copper salt, and “additive / metal salt” represents the molar ratio of the additive to the total amount of the copper salt and the doping metal salt;

[0122] 2. "Treatment conditions" refers to the microwave treatment conditions used in the preparation of catalysts in Application Examples 1 to 16 and Application Comparative Examples 1 to 4; Application Comparative Example 5 refers to the calcination conditions; Application Comparative Example 6 refers to the catalyst prepared by the coprecipitation method and the calcination conditions used;

[0123] 3. “100%” means that no characteristic peak of the substrate is detected during gas chromatography analysis, indicating that the substrate in the reaction system is completely converted, the same below.

[0124] As shown in Table 1, the lanthanide metal-doped copper-based oxides prepared by microwave-assisted methods in Examples 1 to 16 were used as hydrodeoxygenation catalysts to catalyze the hydrogenation of vanillin, which effectively improved the conversion rate and the yield of the target product MMP.

[0125] Comparative Application Example 3 shows that when copper oxide (Cat-D3) is used alone as the catalyst without the addition of a doping metal, the vanillin conversion rate is less than 50%, and almost no target product (MMP) is produced. This indicates that undoped copper oxide is incapable of catalyzing the deoxygenation of vanillin. Comparing Application Example 1 with Comparative Application Examples 2-3, it is clear that doping copper-based catalysts with lanthanide metals, compared to Co and Al, enhances catalytic activity and improves selectivity for the target product, MMP.

[0126] Comparing Application Example 1 with Comparative Examples 5 to 6, it can be seen that when the copper-based catalyst (Cat-1) prepared with microwave assistance is used to catalyze the hydrodeoxygenation reaction of vanillin, the yield of MMP is at least 15% higher than that of the copper-based catalysts (Cat-D5 and Cat-D6) prepared by high-temperature calcination. This indicates that microwave-assisted preparation of lanthanide metal-doped copper oxide is more conducive to improving the deoxygenation efficiency of vanillin.

[0127] Comparing Application Example 1 with Application Examples 2 to 6, it can be seen that compared with other lanthanide metals, praseodymium as the doping metal exhibits higher selectivity for the target product MMP.

[0128] Application Examples 17-20

[0129] Vanillin hydrodeoxygenation was carried out according to the method of Application Example 1, except that the solvent methanol was replaced with ethanol, n-propanol, isopropanol, and isobutanol, respectively. The mixed solution was subjected to gas chromatography analysis, and the test results are listed in Table 2.

[0130] Table 2

[0131]

[0132] As shown in Table 2, replacing methanol with other linear alcohol solvents as the hydrogen source can also improve the deoxygenation efficiency of vanillin. In particular, when isopropanol and isobutanol are used as solvents, the yield of the target product MMP can reach more than 91%.

[0133] Application Examples 21-23

[0134] 0.3 g of biomass compound and 30 mL of isopropanol were added to a 100 mL high-temperature autoclave and stirred until the compound dissolved. 0.2 g of catalyst Cat-1 was then added. The autoclave was then sealed and heated to different temperatures under vigorous stirring (600 rpm). The reaction was allowed to proceed at this temperature for 3 h. After the reaction was completed, the mixture was cooled to room temperature to obtain a mixed solution containing the product, which was then analyzed by gas chromatography.

[0135] The biomass compounds, reaction temperature, target product structure, and gas chromatography test results are listed in Table 3.

[0136] Application Comparative Example 7

[0137] The vanillin was subjected to the hydrodeoxygenation reaction according to the method of Application Example 21, except that the catalyst Cat-1 was replaced by the catalyst Cat-D1 prepared in Comparative Example 1. The reaction mixture was analyzed by gas chromatography, and the test results are listed in Table 3.

[0138] Application Comparative Example 8

[0139] The ethyl vanillin was subjected to the hydrodeoxygenation reaction according to the method of Application Example 22, except that the catalyst Cat-1 was replaced by the catalyst Cat-D2 prepared in Comparative Example 2. The reaction mixture was analyzed by gas chromatography, and the test results are listed in Table 3.

[0140] Table 3

[0141]

[0142] As can be seen from Table 3, the praseodymium-doped modified copper oxide compound (Cat-1) of Example 1 is also suitable for the hydrodeoxygenation conversion of biomass compounds such as vanillin, ethyl vanillin, and 5-hydroxymethylfurfural, and the yield of the target product is more than 80%.

[0143] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a copper-based catalyst, characterized in that: include: (1) mixing copper salt, doping metal salt and auxiliary agent and grinding them uniformly to obtain a grinding product; wherein, The doping metal in the doping metal salt is M, M represents a lanthanide metal, and the auxiliary agent is an organic acid and / or a polyol; (2) subjecting the ground product to microwave treatment to form a copper-based oxide doped with M, thereby obtaining a copper-based catalyst.

2. The preparation method according to claim 1, characterized in that The copper salt is copper nitrate.

3. The preparation method according to claim 1 or 2, characterized in that M is selected from La, Ce, Pr, Nd, Sm or Gd; Preferably, the doping metal salt is a nitrate of a lanthanide metal; Preferably, the molar ratio of the doping metal salt to the copper salt is (0.005-0.2):1, more preferably (0.01-0.2):

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that The molar ratio of the auxiliary agent to the total amount of the copper salt and the doping metal salt is (0.1-0.4):1; Preferably, the auxiliary agent is an organic acid and / or polyol; Preferably, the auxiliary agent is at least one of ascorbic acid, citric acid, malic acid and xylitol.

5. The preparation method according to any one of claims 1 to 4, characterized in that The power of the microwave treatment is 400-800W, and the treatment time is 30-300s.

6. A copper-based catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the copper-based catalyst according to claim 6 in catalyzing the hydrodeoxygenation reaction of oxygen-containing organic matter.

8. The use according to claim 7, characterized in that The oxygen-containing organic matter is selected from biomass compounds; Preferably, the biomass compound is at least one of vanillin, o-vanillin, ethyl vanillin, cinnamaldehyde, benzaldehyde, 5-hydroxymethylfurfural, methyl levulinate and ethyl levulinate.

9. The use according to claim 7 or 8, characterized in that The application comprises: in the presence of the copper-based catalyst, subjecting the oxygen-containing organic matter to a hydrodeoxygenation reaction in the presence of an alcohol solvent; Preferably, the alcohol solvent is at least one of methanol, ethanol, n-propanol, isopropanol and isobutanol. Preferably, the amount of the alcohol solvent used is such that the concentration of the oxygen-containing organic matter in the alcohol solvent is 5 to 50 g / L.

10. The use according to any one of claims 7 to 9, characterized in that: The mass ratio of the copper-based catalyst to the oxygen-containing organic matter is (0.5-0.8):1; Preferably, the hydrodeoxygenation reaction is carried out under stirring conditions, the reaction temperature is 180-220° C., the reaction time is 0.5-8 h, and the stirring speed is 500-800 rpm.

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