Carbon-modified nickel-based catalyst and application thereof in catalytic hydrogenation of lignin derivatives

Abstract

The present application relates to a kind of carbon modified nickel-based catalyst and application in lignin derivative catalytic hydrogenation, belong to the preparation technology of nanometer catalyst and biomass derivative catalytic conversion technical field.The present application uses cellulose as template agent, and synthesizes hydrotalcite-like precursor using in-situ precipitation growth method, after carbonaceous reduction in inert atmosphere, carbon modified nickel-based nanometer catalyst is prepared.In addition, precursor (1) without adding cellulose is physically mixed with cellulose, and carbonaceous reduction under inert atmosphere, or, (2) direct calcination under inert atmosphere or reducing atmosphere, then after post-carbon treatment, carbon modified nickel-based nanometer catalyst with different particle size and carbon content can be prepared.The carbon modified nickel-based nanometer catalyst provided by the present application has universal applicability for lignin derivative hydrodeoxygenation reaction, and has the characteristics of mild reaction condition, high conversion rate and selectivity, fast reaction rate, good repeatability and the like.

Description

Technical Field

[0001] This invention belongs to the field of catalytic hydrogenation technology of lignin derivatives, specifically relating to a method for preparing a carbon-modified nickel-based catalyst, and the application of the catalyst in the catalytic hydrogenation and quality improvement of lignin derivatives. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Carbon in carbon dioxide is fixed by plants through photosynthesis, producing approximately 170 billion tons of lignocellulose annually. Efficiently converting these abundant renewable natural resources into desired products could effectively alleviate human dependence on fossil fuels and address increasingly prominent environmental problems. Lignin is one of the main components of lignocellulose (accounting for 15-30% by weight and 40% energy), and is also a major byproduct of the paper industry and the ethanol production process from the hydrolysis and fermentation of lignocellulose biomass. However, due to insufficient utilization, much of it becomes an environmental pollutant. Lignin is the only non-petroleum resource in nature that can provide renewable aromatic compounds, and it can be decomposed into phenolic compounds (called bio-oils) through various pathways. However, the high oxygen content in lignin molecules results in bio-oils with low energy density, high viscosity, and unstable combustion, making them difficult to utilize directly. For example, vanillin (4-hydroxy-3-methoxybenzaldehyde) contains three typical functional groups (aldehyde, ether, and hydroxyl) found in lignin fractions, making it a typical component extracted from lignin fractions. However, because vanillin molecules contain phenolic hydroxyl groups and have aromatic aldehyde substitutions at the para position, they exhibit reducing properties, are easily oxidized, and have poor thermal stability. Therefore, developing efficient biomass conversion technologies to convert lignin into high-value-added chemicals or liquid fuels will help avoid resource waste, protect the environment, and further reduce human dependence on fossil resources.

[0004] Hydrodeoxygenation (HDO) technology is an effective method for upgrading and improving bio-oils, offering advantages such as high calorific value and low coking. Vanillin can be converted to 2-methoxy-4-methylphenol (MMP) via the HDO reaction. MMP is widely used as an intermediate in fragrances, pharmaceuticals, and other valuable chemicals, and is also a promising biomass fuel. Therefore, the HDO reaction of vanillin can serve as an important model reaction for studying the value-added processing of lignin-based biomass resources, and is of great significance for the value-added processing of lignin-based biomass resources. However, in the catalytic HDO system, the accompanying side reaction (further demethylation to generate 2-methoxyphenol) reduces the selectivity of MMP. Therefore, designing and synthesizing a highly active and selective catalyst system to achieve the directed conversion of vanillin is essential.

[0005] Initially, γ-Al₂O₃-supported CoMo (NiMo) sulfide catalysts used in petroleum refining were employed for vanillin HDO reactions. However, during use, sulfur loss from sulfide catalysts leads to product contamination and quality degradation, and the interaction between sulfides and oxygen can alter the catalyst structure or even cause deactivation. While noble metal catalysts such as Pt and Pd exhibit high catalytic activity, their high cost and scarcity limit their large-scale application. In recent years, transition metal Ni catalysts have been widely used in phenolic HDO reactions, becoming an important research direction in bio-oil HDO catalysts. Although Ni catalysts have high activity, they are prone to saturation hydrogenation of the benzene ring. Furthermore, since water is often used as a green solvent, biomass upgrading in the aqueous phase is a future direction for green and sustainable chemistry. However, during the recycling of Ni catalysts in the aqueous phase, the active metal sites are prone to sintering, loss, and oxidation, leading to catalyst deactivation. Therefore, achieving efficient and directional HDO of vanillin in water using transition metal Ni catalysts remains a challenge.

[0006] Related studies have shown that modifying metal-based catalysts by doping or depositing carbon can improve their activity, selectivity, and stability. Cellulose is the most widely distributed and abundant polysaccharide in nature, accounting for more than 50% of the carbon content in the plant kingdom. If cellulose can be used as a carbon source to modify Ni-based catalysts and applied to the vanillin HDO reaction, it is expected to provide a new green catalytic conversion method that "takes from wood and uses wood" for the full utilization and high-value conversion of lignocellulosic biomass resources. The inventors' prior research provided a Ni-based catalyst and its preparation method, as well as its application in reductive amination (application number 202110919247.3). However, this patent uses phenolic resin spheres of approximately 180 nm as template agents, with an outer layer of hydrotalcite. The phenolic resin spheres used in this method are relatively small and easily embedded in the hydrotalcite, while cellulose particles are larger, at least at the micrometer level, making the formation of the corresponding hydrotalcite coating layer technically challenging. In addition, the catalysts in the aforementioned patents are used for the hydrogenation reduction of aldehydes / ketones and cannot achieve the catalytic effect in aqueous solvents. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a carbon-modified nickel-based nanocatalyst, its preparation method, and its application in lignin derivative HDO. This invention uses cellulose as a template, reducing agent, and carbon source, employing an in-situ precipitation growth method to synthesize a hydrotalcite-like precursor. After carbon reduction treatment in an inert atmosphere, a carbon-modified nickel-based nanocatalyst with controllable carbon content and uniform size is prepared. Furthermore, by physically mixing the precursor synthesized without cellulose (1) with cellulose and reducing it under an inert atmosphere, or (2) directly calcining it under an inert or reducing atmosphere, followed by subsequent carbon supplementation, a carbon-modified nickel-based nanocatalyst with controllable carbon content and uniform size can be prepared. The carbon-modified nickel-based nanocatalyst provided by this invention, employing a novel green catalytic conversion method of "taking from wood and using it back to wood," has broad applicability to the HDO reaction of lignin derivatives in water, and features mild reaction conditions, fast reaction rate, high conversion and selectivity, and good catalyst reusability.

[0008] In a first aspect, a method for providing a small-sized carbon-modified nickel-based nanocatalyst is provided, comprising the following steps:

[0009] A metal precursor solution and an alkaline solution were added to a modified cellulose solution to obtain a precursor I solution. After aging, filtration, washing, and drying, catalyst precursor I was obtained. The precursor I was subjected to carbon reduction treatment under an inert atmosphere to obtain a carbon-modified nickel-based nanocatalyst.

[0010] The modified cellulose is prepared as follows: cellulose, metal salt M auxiliary agent, and ammonia solution are mixed and heated. The metal element in the metal salt M auxiliary agent is selected from one or more of Ni, Co, Mg, Cu, Zn, Al, Fe, Zr, and Ti.

[0011] The metal precursor solution is a solution containing Ni and X elements, wherein X is selected from one or more of Al, Fe, Zr, and Ti;

[0012] The alkaline solution is selected from one of the following: 0.05–2.5 mol / L NaOH, 0.2–3.2 mol / L Na2CO3, 0.05–3.2 mol / L NaHCO3, or a mixture of two of them.

[0013] The cellulose particles have a diameter of approximately 25 micrometers, which, compared to the phenolic resin spheres in the prior patent, exhibits a larger particle size and surface area. Those skilled in the art would find it difficult to anticipate the formation of a uniformly covering hydrotalcite layer on the cellulose surface. In this invention, the inventors discovered that the cellulose modified with the aforementioned metal ions can, based on strong electrostatic interactions, allow the formation of a uniform layer of Ni. 2+ X n+ Other metal ion additives are uniformly adsorbed onto the cellulose surface, thereby obtaining a uniformly distributed hydrotalcite-like surface.

[0014] In the preparation of the modified cellulose described above, the present invention also has the following preferred embodiments:

[0015] The metal salt M auxiliary is selected from one or more of nitrates, chlorides, acetates, acetylacetones, cyanides, carbonyl salts, etc.

[0016] Since the cellulose content affects the particle size and carbon content of the final carbon-modified nickel-based nanocatalyst, in a preferred embodiment, the concentration of cellulose is 0-100 g / L, preferably 15-25 g / L.

[0017] The concentration of the metal salt M auxiliary agent is 0.06 to 2.5 mmol / L, more preferably between 0.06 and 1.5 mmol / L, and even more preferably between 0.3 and 0.8 mmol / L.

[0018] The ammonia solution is prepared by mixing concentrated ammonia and water. The concentrated ammonia is 25-32% ammonia and the volume ratio of concentrated ammonia to water is 1:(1-40), preferably 1:(5-15).

[0019] In a further preferred embodiment, the modified cellulose can be prepared by heating. The heating temperature is 50-160°C, preferably 80-130°C; the heating time is 6-25 hours, preferably at least 1 hour, and more preferably at least 4 hours, so as to achieve uniform adsorption of metal ions on the cellulose surface. Considering energy consumption costs, it generally does not exceed 8 hours, preferably not more than 6 hours.

[0020] It has been verified that the cellulose modified in the above manner can form a homogeneous solution when dispersed in water or alcohol solvent. Therefore, the solvent in the modified cellulose solution is selected from one or more of water, methanol, ethanol, n-propanol, isopropanol, and isobutanol, with methanol being preferred.

[0021] Regarding the aforementioned metal precursor solution, the present invention also has the following preferred embodiments:

[0022] In one embodiment, the Ni and X precursors are selected from one or more of nitrates, chlorides, acetates, acetylacetones, cyanides, and carbonyl salts; wherein the molar ratio of Ni to X is (1-8):1, preferably (3-6):1, and more preferably 3:1;

[0023] The total concentration of the Ni and X precursors is 0.05–10 mol / L. When the total metal concentration of the Ni and X precursors is below 0.05 mol / L, the metal loading is extremely low, making it unsuitable for practical production applications. When the metal salt concentration is above 10 mol / L, the metal loading is extremely high, and the active component is prone to sintering. More preferably, the total metal concentration of Ni and X precursor I is between 0.6 and 5 mol / L.

[0024] In another embodiment, the metal precursor solution contains, in addition to Ni and X precursors, a Y precursor, wherein Y is one or more selected from Co, Mg, Cu, Zn, etc., and the Y precursor is a divalent metal salt. 2+ Metal ions and Ni 2+ It can form a similar structure to hydrotalcite.

[0025] When solution B contains Ni, X, and Y precursors, the Ni, X, and Y precursors may be selected from one or more of nitrates, chlorides, acetates, acetylacetones, cyanides, and carbonyl salts, respectively; wherein the molar ratio of (Ni+Y) to X is (1-8):1, preferably (3-6):1; the molar ratio of Y to Ni is (0-50):1, preferably (5-15):1; and the total concentration of the Ni, X, and Y precursors is 0.01-10 mol / L, preferably 0.6-5 mol / L.

[0026] In addition, the solvent of the metal precursor solution is an alcohol solution, wherein the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, isobutanol, n-butanol, 2-butanol, cyclohexanol, ethylene glycol, etc., preferably methanol, and the volume ratio of alcohol to water in the alcohol solution is (0-20):(1-30).

[0027] In the preparation of the above-mentioned precursor I solution, the metal precursor solution and the alkaline solution should be added dropwise to the modified cellulose solution simultaneously at a rate of 10-100 mL / min, preferably 20-40 mL / min, and more preferably 25-35 mL / min. The temperature can be appropriately increased during the dropwise addition process to improve the dispersion effect, and the dropwise addition temperature is 40-70℃.

[0028] In addition, the pH of the precursor I solution needs to be adjusted during the above-mentioned dropwise addition process, and the pH should be controlled between 7 and 11. The pH value can be determined according to Ni. 2+ X n+ The Ksp value is used to determine complete precipitation. If the alkali content is too low, the ions in the solution cannot be completely precipitated; a slightly excessive amount of alkali promotes better co-precipitation; however, if the alkali content is too high, the crystals will be too large. Further optimization involves controlling the pH between 9 and 10.

[0029] The aging temperature of the above-mentioned precursor I solution is 30–160°C, preferably 50–110°C, and more preferably 50–65°C; the aging time is 8–48 h, and more preferably 10–18 h.

[0030] The inert gas is one or more of nitrogen, argon, and helium.

[0031] The carbon reduction temperature is 200–1100℃, preferably 400–1000℃, more preferably 500–950℃, and even more preferably 550–850℃.

[0032] Secondly, a method for providing a large-particle-size carbon-modified nickel-based nanocatalyst includes the following steps: simultaneously adding a metal precursor solution and an alkaline solution to an alcohol solvent to obtain a precursor II solution; physically mixing precursor II with cellulose; and obtaining the carbon-modified nickel-based nanocatalyst using any of the following treatment methods:

[0033] (1) Calcination under an inert atmosphere;

[0034] (2) Precursor II is calcined in an inert atmosphere and then subjected to a subsequent carbon supplementation treatment.

[0035] (3) The precursor II is calcined and reduced in a reducing atmosphere, and then subjected to a subsequent carbon supplementation treatment.

[0036] In the preparation of precursor II solution, the metal precursor solution, alkali solution, and alcohol solvent are set in the same way as in the first aspect, that is, the only difference between precursor II solution and precursor I solution is that modified cellulose is not added.

[0037] All three treatment methods can obtain carbon-modified nickel-based nanocatalysts, but the size and carbon content of the catalysts differ. In schemes (1) and (2), the carbon-modified nickel-based catalyst with larger particle size is obtained under an inert atmosphere, and its main product for catalyzing the hydrogenation of vanillin is vanillyl alcohol (HMP). In scheme (3), the carbon-modified nickel-based catalyst with smaller particle size is obtained under a reducing atmosphere, and its main product for catalyzing the hydrogenation of vanillin is MMP.

[0038] In the above schemes (1)-(3), the roasting and carbonization temperature is 200-1100℃, preferably 400-1000℃, more preferably 500-950℃, and even more preferably 550-850℃; the roasting and carbonization time is 0.8-20h, more preferably 1.2-12h, and even more preferably 2-4h. In order to achieve sufficient roasting and carbonization, the roasting and carbonization time is generally at least 0.8h, and even more preferably at least 2h. Considering energy consumption costs, it is generally no more than 12h, and preferably no more than 4h.

[0039] In the above schemes (1) and (2), the inert gas is one or more of nitrogen, argon and helium.

[0040] In the above schemes (2) and (3), the reducing gas is one or more of methanol volatile gas, ethanol volatile gas, isopropanol volatile gas, hydrogen, CO, and CH4; the carbon source for carbon supplementation is one or more of cellulose, polymer, CO, CH4, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, polymethyl methacrylate, citric acid, oleic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, malic acid, gluconic acid, pyromellitic acid, sawdust, and straw.

[0041] Thirdly, a small-sized carbon-modified nickel-based nanocatalyst prepared by the method described in the first aspect, or a large-particle-size carbon-modified nickel-based nanocatalyst prepared by the method described in the second aspect, is provided.

[0042] Fourthly, a catalytic hydrogenation method for lignin derivatives is provided, wherein water is used as a solvent, and the carbon-modified nickel-based nanocatalyst described in the third aspect is added to the lignin derivative substrate, and hydrogen gas is introduced to carry out the reaction.

[0043] The lignin derivative is one or more of vanillin, benzaldehyde, eugenol, p-phenylenediamine, vanillin ethyl ketone, and benzylphenyl ether, and the product obtained by the above method is MMP, toluene, 3,5-dimethoxy-4-hydroxytoluene, p-xylene, 4-ethylguaiacol, toluene, and phenol, in sequence.

[0044] Preferably, the mass ratio of carbon-modified nickel-based nanocatalyst to lignin derivative is 1:(0.05-25), more preferably 1:(5-12), and even more preferably 1:(6-10).

[0045] The concentration of the lignin derivative is preferably 0.1–10 mol / L.

[0046] The preferred reaction temperature is 80–150℃.

[0047] The reaction time is preferably 0.5 to 10 hours at the reaction temperature. To achieve a complete reaction, the reaction time is generally at least 0.5 hours, more preferably at least 1.5 hours. Considering cost, the reaction time is generally no more than 10 hours, preferably no more than 6 hours, and more preferably no more than 4 hours. The specific reaction time may be adjusted according to the reaction temperature and solution composition.

[0048] In a preferred embodiment, the method further includes a catalyst regeneration step: after the reaction, the catalyst is recovered by centrifugation, washed with water 1 to 3 times, washed with alcohol 1 to 3 times, and dried to obtain the regenerated catalyst;

[0049] Preferably, the alcohol detergent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, and cyclohexanol. Attached Figure Description

[0050] 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 improper limitation of the invention.

[0051] Figure 1 This is the synthetic route for the carbon-modified nickel-based catalyst described in this invention;

[0052] Figure 2 TEM images of the carbon-modified nickel-based catalysts of Examples 1-4 with a particle size of approximately 8 nm and a carbon content of approximately 0.7 wt%.

[0053] Figure 3 TEM images of carbon-modified nickel-based catalysts with a particle size of approximately 18 nm and a carbon content of approximately 0.8 wt% from Examples 1-5;

[0054] Figure 4 XPS spectra of a nickel catalyst prepared by the conventional hydrogen reduction method and a carbon-modified nickel catalyst prepared in this patent before and after 10 cycles of use;

[0055] Figure 5 This is a SEM image of the carbon-modified nickel-based catalyst in this invention;

[0056] Among them, (a) is a cellulose uniformly covered with hydrotalcite, and (b) is a magnified view of a local part of the surface;

[0057] Figure 6 This is a comparison chart of the recycling performance of the carbon-modified nickel-based catalyst in this invention;

[0058] (a) represents the carbon-modified nickel-based catalyst of this invention, and (b) represents the recycling performance of a conventional nickel catalyst. Detailed Implementation

[0059] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0060] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0062] Example 1-1

[0063] In this embodiment, a carbon-modified nickel-based catalyst and a method for catalytic hydrogenation of vanillin based on the catalyst are provided:

[0064] Add 0.1 g cellulose, 0.010 mmol of metal salt M (one of Co, Fe, or Ni nitrate), 8 mL concentrated ammonia, and 30 mL deionized water to a dry container. React at 60 °C for 4 h. After the reaction is complete, filter, wash, and dry to obtain surface-modified cellulose. Disperse the surface-modified cellulose in 50 mL methanol to obtain cellulose dispersion A.

[0065] Press [Ni 2+ ] and [Al 3+ A mixed salt solution with an atomic ratio of 3:1 and a total metal concentration of 0.2 mol / L was prepared, wherein the volume ratio of methanol to water was 1:20, resulting in solution B.

[0066] A mixed alkaline solution of 0.2 mol / L NaOH and 0.4 mol / L Na2CO3 was prepared as a precipitant to obtain solution C.

[0067] At 70℃, solutions B and C were simultaneously added dropwise to dispersion A, with the addition rate of solution C controlled at 20 mL / min, maintaining the pH of the mixed solution at 10.0. After the addition of solution B was complete, aging continued for 12 h. The aged suspension was filtered, washed, and vacuum dried at 60℃ for 8 h to obtain the catalyst precursor.

[0068] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and carbonized at 800°C for 3 hours under an argon atmosphere. After cooling to room temperature and passivation for 1 hour, a carbon-modified nickel-based catalyst was obtained.

[0069] 0.02 g of the carbon-modified nickel-based catalyst obtained above, 1 mmol of vanillin, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130 °C for 2 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 1.

[0070] Examples 1-2

[0071] The difference from Example 1-1 is that the metal M auxiliary is 0.010 mmol nickel nitrate. In addition to investigating the nickel nitrate to aluminum nitrate atomic ratio of 3:1 (Example 1-1), 2:1 and 4:1 were also investigated. The remaining catalyst synthesis conditions and vanillin catalytic hydrogenation reaction conditions were the same as in Example 1-1.

[0072] Examples 1-3

[0073] The preparation of the catalyst precursor is the same as in Examples 1-2.

[0074] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and carbonized at 300–600 °C for 3 h under an argon atmosphere. After cooling to room temperature and passivation for 2 h, a carbon-modified nickel catalyst was obtained.

[0075] The synthesis conditions for the remaining catalysts and the conditions for the vanillin catalytic hydrogenation reaction were the same as in Example 1-1.

[0076] Examples 1-4

[0077] The difference from Example 1-1 is that the metal M promoter is 0.010 mmol nickel nitrate; the rest of the catalyst synthesis conditions are the same as in Example 1-1, yielding a carbon-modified nickel catalyst with a particle size of approximately 8 nm and a carbon content of approximately 0.7 wt%, the specific morphology of which is as follows. Figure 2 As shown.

[0078] 0.02 g of the carbon-modified nickel catalyst obtained above, 1 mmol of benzaldehyde, eugenol, p-phenylenediamine, vanillin, benzylphenyl ether, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130–150 °C for 1–6 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 1.

[0079] Examples 1-5

[0080] In this embodiment, the preparation of the catalyst precursor is the same as in Examples 1-2, except that cellulose is not added. The catalyst precursor prepared above is physically mixed with 0.1g of cellulose and placed in a quartz tube of a tube furnace. Carbon reduction is performed at 800℃ for 3 hours under an argon atmosphere. After cooling to room temperature and passivation for 1 hour, a carbon-modified nickel catalyst with a particle size of approximately 18nm and a carbon content of approximately 0.8wt% is obtained. The specific morphology is as follows: Figure 3 As shown.

[0081] The catalytic hydrogenation conditions for vanillin were the same as in Examples 1-1, except that the heating time was 6 hours. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 1.

[0082] Examples 1-6

[0083] The preparation of carbon-modified nickel catalysts is the same as in Examples 1-4.

[0084] 0.02 g of carbon-modified nickel catalyst, 1 mmol of vanillin, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130 °C for 1 h and 4 h, respectively. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was determined by gas chromatography, and the results are shown in Table 1.

[0085] Example 2-1

[0086] Add 0.1 g cellulose, 0.010 mmol of metal salt M (one of cobalt, iron, or zirconium nitrate), 8 mL concentrated ammonia, and 30 mL deionized water to a dry container. React at 60 °C for 4 h. After the reaction is complete, filter, wash, and dry to obtain surface-modified cellulose. Disperse the surface-modified cellulose in 50 mL methanol to obtain cellulose dispersion A.

[0087] Press [Ni 2+ ] and [Fe 3+ A mixed salt solution with an atomic ratio of 3:1 and a total metal concentration of 0.2 mol / L was prepared, wherein the volume ratio of methanol to water was 1:30, resulting in solution B.

[0088] A mixed alkaline solution of 0.2 mol / L NaOH and 0.4 mol / L Na2CO3 was prepared as a precipitant to obtain solution C.

[0089] At 70℃, solutions B and C were simultaneously added dropwise to dispersion A, with the addition rate of solution C controlled at 25 mL / min, maintaining the pH of the mixed solution at 9.8. After the addition of solution B was complete, aging continued for 12 h. The aged suspension was filtered, washed, and dried at 60℃ for 8 h to obtain the catalyst precursor.

[0090] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and reduced with carbon at 800°C for 3 hours under an argon atmosphere. After cooling to room temperature and passivating for 1 hour, a NiFeC-based catalyst was obtained.

[0091] 0.1 g of the NiFeC-based catalyst obtained above, 1 mmol of vanillin, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130 °C for 1 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 2.

[0092] Example 2-2

[0093] The difference from Example 2-1 is that the metal salt M additive is nickel nitrate, and the [Ni 2+ ] and [Fe3+ The atomic ratio is (2-4):1, and the synthesis conditions for the remaining catalysts and the catalytic synthesis conditions for vanillin are the same as in Example 2-1.

[0094] Example 3

[0095] 0.1 g cellulose, 0.010 mmol nickel nitrate, 8 mL concentrated ammonia, and 30 mL deionized water were added to a dry container and reacted at 60 °C for 4 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain surface-modified cellulose. The surface-modified cellulose was dispersed in 50 mL methanol to obtain cellulose dispersion A.

[0096] Press [Ni 2+ ] and [X n+ The atomic ratio is 3:1 (specifically X) n+ See Table 3). Prepare a mixed salt solution with a total metal concentration of 0.2 mol / L, wherein the volume ratio of methanol to water is 1:30, to obtain solution B.

[0097] A mixed alkaline solution of 0.2 mol / L NaOH and 0.4 mol / L Na2CO3 was prepared as a precipitant to obtain solution C.

[0098] At 70℃, solutions B and C were simultaneously added dropwise to dispersion A, with the addition rate of solution C controlled at 25 mL / min, maintaining the pH of the mixed solution at 9.8. After the addition of solution B was complete, aging continued for 12 h. The aged suspension was filtered, washed, and dried at 60℃ for 8 h to obtain the catalyst precursor.

[0099] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and reduced with carbon at 800°C for 3 hours under an argon atmosphere. After cooling to room temperature and passivating for 1 hour, a Ni-XC-based catalyst was obtained.

[0100] 0.1 g of Ni-XC-based catalyst, 1 mmol of vanillin, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130 °C for 1 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was determined by gas chromatography, and the results are shown in Table 3.

[0101] Example 4

[0102] The difference from Example 3 is that, according to [Ni 2+ ]:[Y 2+ ]:[Xn + A Ni-X-YC-based catalyst was obtained with an atomic ratio of 2:1:1 (Y and X are shown in Table 4 for details), and the rest of the settings were the same as in Example 3.

[0103] Example 5-1

[0104] Add 50 mL of methanol to a dry container to obtain solvent A.

[0105] Press [Ni 2+ ] and [Al 3+ A mixed salt solution with an atomic ratio of 3:1 and a total metal concentration of 0.2 mol / L was prepared, wherein the volume ratio of methanol to water was 1:20, resulting in solution B.

[0106] A mixed alkaline solution of 0.2 mol / L NaOH and 0.4 mol / L Na2CO3 was prepared as a precipitant to obtain solution C.

[0107] At 70℃, solutions B and C were simultaneously added dropwise to dispersion A, with the addition rate of solution C controlled at 20 mL / min, maintaining the pH of the mixed solution at 10.0. After the addition of solution B was complete, aging continued for 12 h. The aged suspension was filtered, washed, and vacuum dried at 60℃ for 8 h to obtain the catalyst precursor.

[0108] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and calcined at 800°C for 3 hours under an argon atmosphere. After cooling to room temperature and passivating for 1 hour, 0.1 g of cellulose was added for carbon supplementation to obtain a carbon-modified nickel catalyst with a larger particle size.

[0109] 0.02 g of the carbon-modified nickel catalyst obtained above, 1 mmol of vanillin, 10 mL of water, and 1.0 MPa of hydrogen gas were added to the reactor, and the mixture was heated at 130 °C for 2 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 5.

[0110] Example 5-2

[0111] The catalyst precursor is the same as in Example 5-1, except that the catalyst precursor prepared above is placed in a quartz tube of a tube furnace, reduced at 800°C for 3 hours in a hydrogen atmosphere, cooled to room temperature and passivated for 1 hour, and then 0.1 g of cellulose is added for carbon supplementation to obtain a carbon-modified nickel catalyst with a smaller particle size.

[0112] The remaining settings are the same as in Example 5-1.

[0113] Example 6

[0114] Add 50 mL of methanol to a dry container to obtain solvent A.

[0115] Press [Ni 2+ ] and [Al 3+ A mixed salt solution with an atomic ratio of 3:1 and a total metal concentration of 0.2 mol / L was prepared, wherein the volume ratio of methanol to water was 1:20, resulting in solution B.

[0116] A mixed alkaline solution of 0.2 mol / L NaOH and 0.4 mol / L Na2CO3 was prepared as a precipitant to obtain solution C.

[0117] At 70℃, solutions B and C were simultaneously added dropwise to dispersion A, with the addition rate of solution C controlled at 20 mL / min, maintaining the pH of the mixed solution at 10.0. After the addition of solution B was complete, aging continued for 12 h. The aged suspension was filtered, washed, and vacuum dried at 60℃ for 8 h to obtain the catalyst precursor.

[0118] The catalyst precursor prepared above was placed in a quartz tube of a tube furnace and calcined at 800°C for 3 hours in an air atmosphere. After cooling to room temperature and passivating for 1 hour, a Ni-Al based metal oxide catalyst was obtained.

[0119] 0.02 g of the Ni-Al based metal oxide catalyst obtained above, 1 mmol vanillin, 10 mL of water, and 1.0 MPa hydrogen pressure were added to the reactor, and the mixture was heated at 130 °C for 2 h. After the reaction was completed, the solid catalyst was separated by magnetic separation. The content of each component in the reaction mixture was detected by gas chromatography, and the results are shown in Table 5. No hydrodeoxygenation products were found.

[0120] Table 1

[0121]

[0122]

[0123] Table 2

[0124]

[0125]

[0126] Table 3 Table 4

[0127]

[0128] Table 5

[0129]

[0130] This invention also investigated the stability of the above-mentioned carbon-modified nickel catalyst. XPS spectra of the nickel catalyst prepared by the conventional hydrogen reduction method and the carbon-modified nickel catalyst prepared in Examples 1-1 were plotted before and after 10 cycles of use. Figure 4 ) and SEM image ( Figure 5 ).like Figure 4As shown, XPS results indicate that the catalyst of this invention was successfully carbon-modified, and a clear peak of nickel carbide appeared in the prepared catalyst; secondly, compared with nickel catalysts prepared by the traditional hydrogen reduction method, the catalyst prepared by this invention has good stability. Figure 6 The catalyst structure remains largely unchanged after repeated use.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for catalytic hydrogenation of a lignin derivative, characterized in that, The method uses water as a solvent, adds a small-sized carbon-modified nickel-based nanocatalyst to the substrate lignin derivative, and then introduces hydrogen gas to carry out the reaction; the lignin derivative is one or more of vanillin, benzaldehyde, eugenol, p-phenylenediamine, vanillin ethyl ketone, and benzylphenyl ether; the products obtained by the above method are, in order, 2-methoxy-4-methylphenol, toluene, 3,5-dimethoxy-4-hydroxytoluene, p-xylene, 4-ethylguaiacol, toluene, and phenol. The small-sized carbon-modified nickel-based nanocatalyst is prepared by a method comprising the following steps: adding a metal precursor solution and an alkaline solution to a modified cellulose solution to obtain a precursor I solution, aging, filtering, washing and drying to obtain catalyst precursor I, and subjecting the catalyst precursor I to carbon reduction treatment under an inert atmosphere to obtain a carbon-modified nickel-based nanocatalyst. The modified cellulose is prepared as follows: cellulose, metal salt M auxiliary agent, and ammonia solution are mixed and heated. The metal salt M auxiliary agent is selected from one or more of nitrates, chlorides, acetates, acetylacetone salts, cyanides, and carbonyl salts. The metal element in the metal salt M auxiliary agent is selected from one or more of Ni, Co, Mg, Cu, Zn, Al, Fe, Zr, and Ti. The metal precursor solution is a solution containing Ni and X elements, wherein X is selected from one or more of Al, Fe, Zr, and Ti; The alkaline solution is selected from one of 0.05 ~ 2.5 mol / L NaOH, 0.2 ~ 3.2 mol / L Na2CO3, 0.05 ~ 3.2 mol / L NaHCO3, or a mixture of two of them.

2. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The concentration of the metal salt M auxiliary agent is 0.06 ~ 2.5 mmol / L.

3. The catalytic hydrogenation method for lignin derivatives as described in claim 2, characterized in that, The concentration of the metal salt M auxiliary agent is between 0.06 and 1.5 mmol / L.

4. The catalytic hydrogenation method for lignin derivatives as described in claim 3, characterized in that, The concentration of the metal salt M auxiliary agent is 0.3 ~ 0.8 mmol / L.

5. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The concentration of the cellulose is 0~100 g / L, and the concentration is not 0.

6. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The ammonia solution is prepared by mixing concentrated ammonia water and water, wherein the concentrated ammonia water is 25-32% ammonia water, and the volume ratio of concentrated ammonia water to water is 1:(1-40).

7. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The preparation process of the modified cellulose requires heating, the heating temperature is 50 ~ 160 o C, the heating time is 6 ~ 25 h.

8. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The solvent in the modified cellulose solution is selected from one or more of water, methanol, ethanol, n-propanol, isopropanol, and isobutanol.

9. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, In the metal precursor solution, the Ni and X precursors are selected from one or more of nitrates, chlorides, acetates, acetylacetones, cyanides, and carbonyl salts; wherein the molar ratio of Ni to X is (1 ~ 8): 1; and the total concentration of the Ni and X precursors is 0.05 ~ 10 mol / L.

10. The catalytic hydrogenation method for lignin derivatives as described in claim 9, characterized in that, The molar ratio of Ni to X is (3~6):

1.

11. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The metal precursor solution contains, in addition to Ni and X precursors, Y precursor, wherein Y is selected from one or more of Co, Mg, Cu, and Zn, and the Ni, X, and Y precursors may be selected from one or more of nitrates, chlorides, acetates, acetylacetones, cyanides, carbonyl salts, etc.; wherein the molar ratio of (Ni + Y) to X is (1 ~ 8): 1; the molar ratio of Y to Ni is (5 ~ 15): 1; and the total concentration of the Ni, X, and Y precursors is 0.01 ~ 10 mol / L.

12. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The solvent of the metal precursor solution is an alcohol solution, wherein the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, isobutanol, n-butanol, 2-butanol, cyclohexanol, and ethylene glycol.

13. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, In the preparation of the precursor I solution, the metal precursor solution and the alkaline solution should be added dropwise to the modified cellulose solution simultaneously at a dropping rate of 10-100 mL / min and a dropping temperature of 40-70°C. o C.

14. The catalytic hydrogenation method for lignin derivatives as described in claim 13, characterized in that, The dropwise addition process also requires adjusting the pH of the precursor I solution, controlling the pH between 7 and 11.

15. The catalytic hydrogenation method for lignin derivatives as described in claim 1, characterized in that, The aging temperature of the precursor I solution is between 30 and 160°C. o C, the aging time is 8 ~ 48 hours; The inert atmosphere is one or more of nitrogen, argon, and helium; The carbonaceous reduction temperature is 200 ~ 1100 °C. o C.

16. A method for catalytic hydrogenation of a lignin derivative, characterized in that, The method uses water as a solvent, adds a large-particle-size carbon-modified nickel-based nanocatalyst to the substrate lignin derivative, and then introduces hydrogen gas to carry out the reaction; the lignin derivative is one or more of vanillin, benzaldehyde, eugenol, p-phenylenediamine, vanillin ethyl ketone, and benzylphenyl ether; the products obtained by the above method are, in order, 2-methoxy-4-methylphenol, toluene, 3,5-dimethoxy-4-hydroxytoluene, p-xylene, 4-ethylguaiacol, toluene, and phenol. The large-particle-size carbon-modified nickel-based nanocatalyst is prepared by a method comprising the following steps: simultaneously adding a metal precursor solution and an alkaline solution to an alcohol solvent to obtain a precursor II solution; physically mixing precursor II with cellulose; and obtaining the carbon-modified nickel-based nanocatalyst by any of the following treatment methods: (1) Calcination under an inert atmosphere; (2) Precursor II is calcined in an inert atmosphere and then subjected to a subsequent carbon addition treatment; (3) Precursor II is calcined and reduced in a reducing atmosphere, and then subjected to subsequent carbon supplementation treatment; The metal precursor solution is a solution containing Ni and X elements, wherein X is selected from one or more of Al, Fe, Zr, and Ti; The alkaline solution is selected from one of 0.05 ~ 2.5 mol / L NaOH, 0.2 ~ 3.2 mol / L Na2CO3, 0.05 ~ 3.2 mol / L NaHCO3, or a mixture of two of them.

17. The catalytic hydrogenation method for lignin derivatives as described in claim 16, characterized in that, In schemes (1)-(3), the roasting and carbonization temperatures are 200~1100℃. o C, roasting and carbonization time is 0.8 ~ 20 h.

18. The catalytic hydrogenation method for lignin derivatives as described in claim 16, characterized in that, In schemes (1) and (2), the inert atmosphere is one or more of nitrogen, argon and helium.

19. The catalytic hydrogenation method for lignin derivatives as described in claim 16, characterized in that, In scheme (3), the reducing atmosphere is one or more of methanol volatile gas, ethanol volatile gas, isopropanol volatile gas, hydrogen, CO, and CH4; the carbon source for carbon supplementation is one or more of cellulose, polymer, CO, CH4, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, polymethyl methacrylate, citric acid, oleic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, malic acid, gluconic acid, pyromellitic acid, sawdust, and straw.

20. The catalytic hydrogenation method for the lignin derivative according to any one of claims 1-19, characterized in that, The mass ratio of carbon-modified nickel-based nanocatalysts to lignin derivatives is 1:(0.05~25); The concentration of lignin derivatives is 0.1 ~ 10 mol / L; The reaction temperature is 80 ~ 150°C. o C; The reaction time is 0.5 to 10 hours.

21. The catalytic hydrogenation method for the lignin derivative according to any one of claims 1-19, characterized in that, The method further includes a catalyst regeneration step: after the reaction, the catalyst is recovered by centrifugation, washed with water 1 to 3 times, then washed with alcohol 1 to 3 times and dried to obtain the regenerated catalyst; the alcohol washing agent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, and cyclohexanol.

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