Method for catalyzing hydrogenolysis of lignin by using modified nitrogen-doped carbon carrier ruthenium-loaded catalyst

Abstract

The invention discloses a method for catalyzing hydrogenolysis of lignin by using a modified nitrogen-doped carbon carrier ruthenium-loaded catalyst. The method comprises the following steps: mixing organic soluble lignin, a modified nitrogen-doped carbon carrier loaded ruthenium catalyst and short-chain monohydric alcohol, and reacting for 2-6 hours at the hydrogen pressure of 1-3 MPa and the temperature of 240-280 DEG C to obtain a monophenol product, the modified nitrogen-doped carbon carrier supported ruthenium catalyst consists of an NC-X carrier and an active component ruthenium, wherein the NC-X carrier is prepared by taking glucose as a carbon source, melamine as a nitrogen source and one of SiO2, Al2O3, K2C2O4 and SBA-15 as a pore forming agent. The catalyst disclosed by the invention can be used for efficiently hydrogenating lignin, the conversion rate of the lignin is up to 89.50%, the total yield of products is 33.22%, the total yield of phenol products is 27.20%, and the catalyst has relatively good cycle stability.

Description

Technical Field

[0001] The present invention relates to the preparation of high-value-added chemicals by catalytic hydrogenolysis of lignin, and specifically to a method for preparing high-value-added chemicals by catalytic hydrogenolysis of lignin using a catalyst modified by a nitrogen-doped carbon carrier loaded with ruthenium using silicon dioxide as a pore-forming agent. The invention belongs to the field of high-value utilization of renewable biomass. Background Art

[0002] The technological revolution based on fossil energy has driven the rapid development of human civilization. However, excessive consumption of fossil resources has led to the release of large amounts of greenhouse gases, causing global warming and environmental pollution. This has led to increasing interest in the production of liquid biofuels, chemicals, and syngas from lignocellulosic biomass, a carbon-neutral, renewable, and abundant raw material. Therefore, the innovative and effective utilization of renewable resources is of great significance to future sustainable development.

[0003] Lignocellulosic biomass is the most abundant naturally renewable source of organic carbon. Composed primarily of three components (cellulose, hemicellulose, and lignin), it is considered a promising alternative to fossil fuels, offering numerous advantages, including availability and carbon neutrality. Lignin, its primary component, is a natural polymer composed primarily of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, along with their derivatives, linked by C-O and C-C bonds. It accounts for 15%–30% of the mass and approximately 40% of the energy of lignocellulosic biomass. Lignin possesses advantages such as a rich aromatic base and high carbon content. Through thermochemical conversion, it can be depolymerized into aromatic compounds, biofuels, and light aromatic hydrocarbons. However, lignin's complex and dense structure makes it difficult to depolymerize selectively into monomeric products.

[0004] At present, the commonly used depolymerization methods for lignin include high-temperature thermal depolymerization, reduction depolymerization, oxidative depolymerization, acid (base) catalytic depolymerization, etc. Among the various catalytic depolymerization technologies, the catalytic reduction depolymerization technology of lignin has attracted widespread attention because of its relatively mild reaction conditions and relatively concentrated distribution of depolymerization products. Lignin has the characteristics of large molecular weight and complex spatial structure. The adaptive carrier pore structure can improve the depolymerization effect of lignin. Carbon materials have the advantages of wide sources, developed pore structure, large specific surface area, and strong adsorption capacity. They are commonly used catalyst carriers in the study of catalytic lignin hydrogenolysis. Introducing nitrogen atoms into the carbon lattice can promote the interaction between the carbon structure and metal particles, enhance the dispersion of active metals, and have high thermal aggregation and leaching stability. In addition, nitrogen doping can also change the acid-base properties of the carrier surface and improve the catalytic activity of the catalyst. It has broad application prospects in various catalytic fields.

[0005] Monophenol products mainly include: They are raw materials for making spices and seasonings, important food additives, and crucial organic synthesis intermediates for a variety of fine chemicals. Currently, the preparation of aromatic hydrocarbons primarily relies on petrochemical routes, which have drawbacks such as harsh conditions, cumbersome procedures, and environmental unfriendliness. Biomass aromatic hydrocarbons, on the other hand, are an important form of renewable, green, clean, and recyclable biomass energy.

[0006] Chinese invention patent CN118439931A discloses the use of a nitrogen-phosphorus co-doped carbon material to catalyze the hydrogenolysis of lignin to produce aromatic hydrocarbon compounds. This application includes the following steps: 1) mixing lignin with a first solvent, transferring the mixture to a hydrothermal reactor, reacting, filtering, rotary evaporating, and drying to obtain treated lignin; 2) adding the nitrogen-phosphorus co-doped carbon material and treated lignin to a high-pressure reactor, adding a second solvent, introducing hydrogen, and heating to react for 10-12 hours; cooling to room temperature; filtering, separating the liquid, and extracting and separating the aromatic hydrocarbon compounds. However, the catalyst used in this technology has a long catalytic reaction time and cumbersome reaction steps. Furthermore, the ethanol / 1,4-dioxane system used in this technology is environmentally polluting.

[0007] Chinese invention patent CN118106001A discloses a zirconium phosphate-supported ruthenium-based catalyst, its preparation method, and its application in catalyzing the hydrogenolysis of lignin. This invention is based on the in-situ reduction of needle-shaped ruthenium oxide supported on amorphous zirconium phosphate to generate elemental ruthenium, constructing a Ru@RuO2 / zirconium phosphate composite nanomaterial. This material can efficiently catalyze the hydrogenolysis of dealkalized lignin and model compounds such as α-O-4 and 4-O-5. The ruthenium nanoparticles generated by in-situ reduction on ruthenium oxide exhibit high stability and can be reused multiple times. However, the hydrothermal reaction in the preparation of this technology catalyst requires 20-30 hours, the preparation process is relatively cumbersome, and the reaction time is as long as 10 hours. The yield of single benzenes is only 23.9%.

[0008] Therefore, there is an urgent need to develop a method for preparing monophenol products by efficient catalytic hydrogenation using lignin, a renewable carbon resource, as raw material, which is low-pollution, simple to prepare, and recyclable. Summary of the Invention

[0009] In response to the problems existing in the prior art, the present invention aims to provide a method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-loaded ruthenium catalyst with mild reaction conditions, environmental friendliness, and high catalytic efficiency, thereby achieving efficient depolymerization of lignin under mild reaction conditions. The lignin conversion rate is 80.90% to 95.70%, and the total product yield is 18.19% to 33.22%, of which the total yield of phenolic products is 14.06% to 27.23%.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst comprises: mixing an organic soluble lignin, a modified nitrogen-doped carbon support-supported ruthenium catalyst, and a short-chain monohydric alcohol, and reacting them at a hydrogen pressure of 1-3 MPa and a temperature of 240-280°C for 2-6 hours to obtain a monophenol product; the modified nitrogen-doped carbon support-supported ruthenium catalyst comprises an NC-X support prepared using glucose as a carbon source, melamine as a nitrogen source, and one of SiO2, Al2O3, K2C2O4, and SBA-15 as a pore-forming agent; and an active component, ruthenium, wherein the ruthenium loading is 1-9 wt.%; and X in the support NC-X represents the N / C molar ratio, which is 5-25.

[0012] To further achieve the purpose of the present invention, preferably, the preparation method of the modified nitrogen-doped carbon support-supported ruthenium catalyst is: fully dissolving the ruthenium source in a solvent, adding the NC-X support for impregnation, standing for 10 to 14 hours, drying, and then placing it under a H2 atmosphere for reduction to obtain a Ru / NC catalyst.

[0013] Preferably, glucose, melamine and a pore-forming agent are fully mixed in a deionized water solution to form a mixed solution, which is then dried, calcined under a nitrogen atmosphere, washed with alkali, and washed with water until neutral to obtain an NC-X carrier.

[0014] Preferably, the calcination method is carried out in a tube furnace, the calcination temperature is 600-1000°C, the heating rate is 2-3°C / min, and the calcination time is 1-2 h;

[0015] The mixed solution is prepared by adding 1-3 g glucose, 7-35 g melamine and 0.5-1.5 g pore-forming agent to every 80 mL deionized water solution; the alkaline washing refers to washing the catalyst with sodium hydroxide solution in order to remove the pore-forming agent.

[0016] Preferably, the ruthenium source is ruthenium acetylacetonate (C 15 H 21 O6Ru), hydrated ruthenium trichloride; the solvent is one of N,N-dimethylformamide (DMF), dichloromethane and acetone.

[0017] Preferably, the reduction under H2 atmosphere is carried out in a vertical tube furnace, the reduction temperature is 300-400°C, and the reduction time is 3-5 h.

[0018] Preferably, the mass ratio of the organolytic lignin to the Ru / NC catalyst modified with the pore-forming agent is 1:0.5 to 1:1.5.

[0019] Preferably, the short-chain monohydric alcohol is one of isopropanol, ethanol and methanol.

[0020] Preferably, the organic soluble lignin is extracted by the following method: adding the lignin raw material and the extract to a reactor, reacting at 100~120°C for 2~6 hours, and then filtering and separating; adding deionized water to the obtained filtrate and filtering to obtain a solid, and drying to obtain the organic soluble lignin; the extract is composed of a mixture of concentrated sulfuric acid, anhydrous ethanol and deionized water, wherein the mass concentration of concentrated sulfuric acid is 95~98%, and 3200~4000 mL of anhydrous ethanol and 800~1000 mL of deionized water are added to every 24 g of concentrated sulfuric acid; 120~150 mL of the extract is added to every 10 g of lignin raw material.

[0021] Preferably, the lignin raw material is derived from any one of bagasse, bamboo, straw, poplar and corn cob; and the phenolic product is one or more of 4-propyl eugenol, 4-ethyl eugenol, 4-propyl guaiacol, 4-ethyl guaiacol and 4-ethylphenol.

[0022] The present invention has the following advantages and beneficial effects compared to the prior art:

[0023] 1) The present invention addresses the current problems of low lignin depolymerization conversion rate and low product yield. By loading metallic ruthenium on a nitrogen-doped carbon support, the lignin conversion rate is achieved to 80.90% to 95.70%, and the total product yield is 18.19% to 33.22%, of which the total yield of phenolic products is 14.06% to 27.23%.

[0024] 2) The nitrogen-doped carbon-supported ruthenium catalyst employed in this invention exhibits excellent catalytic activity. Nitrogen doping enhances the interaction between the support and the metal, improving metal dispersion while reducing metal leaching from the catalyst. Furthermore, nitrogen doping modulates the acid-base sites of the catalyst, further enhancing its catalytic activity.

[0025] 3) During the preparation process of the catalyst used in the present invention, one of SiO2, Al2O3, K2C2O4 or SBA-15 is added as a pore-forming agent to obtain a multi-level porous catalyst with mesopores as the main component. This pore structure is conducive to the mass transfer of macromolecular lignin, thereby improving its reaction activity.

[0026] 4) The catalyst used in this invention is prepared by isovolumetric impregnation, resulting in a simple preparation process. The reaction conditions for lignin depolymerization are mild, with high overall product yields achieved at reaction pressures of 1-3 MPa and temperatures of 240-280°C. This reduces energy consumption and allows for lignin depolymerization under mild conditions.

[0027] 5) The catalyst of the present invention has strong stability and its activity does not decrease significantly after being recycled for 5 times, which is significantly better than existing similar catalysts.

[0028] 6) The catalyst used in the present invention can produce high-value-added chemicals mainly composed of monophenol products under relatively mild conditions, and can realize the high-value utilization of lignin under industrial conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD pattern of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0030] Figure 2 This is the nitrogen adsorption-desorption isotherm of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0031] Figure 3 This is the pore size distribution diagram of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0032] Figure 4 This is the SEM image of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0033] Figure 5 This is a TEM image of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0034] Figure 6 This is the EDS mapping diagram of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0035] Figure 7 This is the Ru 3p spectrum in the XPS spectrum of the 5Ru / NC-10 catalyst in Example 1 of the present invention.

[0036] Figure 8 NH3-TPD diagram of 5Ru / NC-10 catalyst in Examples 1 and 10 of the present invention.

[0037] Figure 9 CO2-TPD diagram of 5Ru / NC-10 catalyst in Examples 1 and 10 of the present invention.

[0038] Figure 10 These are the nitrogen adsorption-desorption isotherms of 5Ru / NC-20 (SiO2), 5Ru / NC-20 (Al2O3), 5Ru / NC-20 (K2C2O4), 5Ru / NC-20 (SBA-15), and 5Ru / NC-20 (without pore former) catalysts in Examples 4, 6, and 9 of the present invention.

[0039] Figure 11This is the pore size distribution diagram of 5Ru / NC-20 (SiO2), 5Ru / NC-20 (Al2O3), 5Ru / NC-20 (K2C2O4), 5Ru / NC-20 (SBA-15), and 5Ru / NC-20 (without pore former) catalysts in Examples 4, 6 to 9 of the present invention.

[0040] Figure 12 This is a GC-MS-FID chart of the preparation of monophenol products by catalytic selective hydrogenolysis of lignin in Example 10 of the present invention. DETAILED DESCRIPTION

[0041] In order to better understand the present invention, the present invention is further described below with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto.

[0042] The phenolic product of the present invention is one or more of 4-propyl syringol, 4-propyl guaiacol, 4-ethyl syringol, 4-ethyl guaiacol and 4-ethylphenol.

[0043] The short-chain monohydric alcohols of the present invention, due to their inherent hydroxyl groups, are excellent hydrogen donors. They also promote hydrogen exchange between the solvent and H₂, facilitating the cleavage of CO bonds in lignin. More importantly, the modified nitrogen-doped carbon support-supported ruthenium catalyst used in the present invention comprises a nitrogen-doped carbon support NC-X and an active component, ruthenium, wherein the ruthenium loading is 1-9 wt.%. The "X" in the support NC-X represents the nitrogen doping level, which is 5-25 mol%. The ruthenium loading of 1-9 wt.% refers to 1-9 wt.% of the total catalyst mass made up of Ru, with the remainder being 91-99 wt.% of the support. The nitrogen incorporation level in the support NC-X is the ratio of the molar amount of N to the molar amount of C. The nitrogen-doped carbon support of this modified nitrogen-doped carbon support-supported ruthenium catalyst has its mesopores increased by the addition of a pore-forming agent. The pore-forming agent is selected from SiO2, Al2O3, K2C2O4, or SBA-15. The addition of the pore-forming agent modulates the catalyst's pore structure, increasing the mesopores. Adjusting the mesopores to an appropriate level greatly facilitates mass transfer of large molecular lignin. Furthermore, the catalyst can also adjust the acidity and alkalinity of the catalyst by adjusting the nitrogen-carbon ratio of the support, further improving its catalytic performance in lignin hydrogenolysis. Specifically, the method for selectively hydrogenating lignin using the modified nitrogen-doped carbon support-supported ruthenium catalyst of the present invention uses lignin as a raw material. After adding a Ru / NC catalyst and an alcohol solvent to the raw material, the reaction conditions are controlled to: H2 pressure of 1-3 MPa, reaction temperature of 240-280°C, and reaction time of 2-6 hours. Lignin can be selectively hydrogenated to produce monophenolic products. Preferably, the short-chain monohydric alcohol of the present invention can be any of methanol, ethanol, or isopropanol.

[0044] The preferred preparation method of the modified nitrogen-doped carbon carrier-supported ruthenium catalyst of the present invention is: ruthenium acetylacetonate (C 15 H 21 O6Ru) or hydrated ruthenium trichloride is fully dissolved in N,N-dimethylformamide (DMF), dichloromethane, or acetone, and then impregnated with a nitrogen-doped carbon support. After impregnation for 20-24 hours, the support is dried in an oven to obtain a precursor. The precursor is then reduced under a H2 atmosphere to yield a ruthenium-based catalyst. The nitrogen-doped carbon support is prepared by thoroughly stirring glucose, melamine, and a pore-forming agent (SiO2, Al2O3, K2C2O4, SBA-15) in a deionized water solution, rotary evaporating, and drying. The resulting solid mixture is placed in a quartz boat, calcined in nitrogen, and washed with alkali to obtain the support NC-X. This calcination is performed in a tube furnace. The calcination temperature, time, carbon source, nitrogen source, and amount of pore-forming agent added can be determined experimentally by those skilled in the art based on the objectives of the invention.

[0045] The lignin extraction method of the present invention is basically a method already disclosed in the prior art. Specifically, the lignin raw material and the extract are added to a reactor, reacted at 100-120°C for 2-6 hours, and then filtered and separated. The resulting filtrate is added with deionized water and filtered to obtain a solid, which is then dried to obtain an organosoluble lignin. The extract is composed of a mixture of concentrated sulfuric acid, anhydrous ethanol, and deionized water. The mass concentration of the concentrated sulfuric acid is 95%-98%, and 3200-4000 mL of anhydrous ethanol and 800-1000 mL of deionized water are added to every 24 g of concentrated sulfuric acid. 120-150 mL of the extract is added to every 10 g of lignin raw material. The lignin raw material is preferably derived from any one of bagasse, corn cob, poplar, and bamboo. The mass ratio of lignin to catalyst is preferably controlled to be 1:0.5-1:1.5.

[0046] This invention addresses the current challenges of lignin hydrogenolysis, including low conversion, low selectivity, harsh reaction conditions, and complex reaction steps. By using a modified nitrogen-doped carbon support-supported ruthenium catalyst and a short-chain monohydric alcohol as solvent, the process achieves efficient lignin depolymerization under conditions of a hydrogen pressure of 1-3 MPa and a temperature of 240-280°C for 2-6 hours. This method achieves a lignin conversion rate of 80.90%-95.70%, and a total product yield of 18.19%-33.22%, including a total yield of phenolic products of 14.06%-27.23%. This method achieves efficient lignin hydrogenolysis under mild reaction conditions.

[0047] Example 1: Preparation of 5Ru / NC-10 (SiO2) catalyst

[0048] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-10 was achieved by a two-step process:

[0049] (1) Preparation of nitrogen-doped carbon support NC-10: Weigh 2 g of glucose (C6H 12 O6), 14 g melamine (C3H6N6), and 1 g silica (SiO2) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-10 support.

[0050] (2) Preparation of 5Ru / NC-10 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-10 catalyst.

[0051] The prepared 5Ru / NC-10 (SiO2) was characterized by X-ray diffraction to explore its crystal structure. Figure 1 As shown in the figure, the catalyst exhibits a broad peak centered at 2θ = 26°, which is attributed to the characteristic peak of the (002) crystal plane of graphitic carbon. Diffraction peaks appear at 2θ of 42.1, 43.4 and 68.1°, which are respectively attributed to the (002), (101) and (110) crystal planes of Ru elemental element, indicating that the active center of the catalyst is elemental ruthenium.

[0052] The prepared 5Ru / NC-10 (SiO2) was characterized by N2-physical adsorption and desorption to explore its pore structure. Figure 2 and Figure 3 As shown. Figure 2 It can be seen that the adsorption isotherm of 5Ru / NC-10 (SiO2) catalyst is a typical type IV isotherm, and an obvious H4 type hysteresis loop can be observed in the medium relative pressure range (P / P0 = 0.4~1.0), indicating that the support has a mesoporous structure. Figure 3 From the pore size distribution diagram, it can be seen that the main pore structure of the carrier is mainly mesopores and macropores.

[0053] Scanning electron microscopy (SEM) was used to characterize the prepared 5Ru / NC-10 (SiO2) to explore its surface morphology. Figure 4It can be clearly observed that the surface morphology of the catalyst is interconnected sheets with a large number of wrinkled structures and random open pores.

[0054] The surface morphology of the prepared 5Ru / NC-10 (SiO2) was investigated using transmission electron microscopy (TEM). Figure 5 As shown in the transmission electron microscopy image of Ru / NC (a in the figure), it can be seen that the Ru metal particles are uniformly dispersed on the catalyst surface. From the high-resolution transmission electron microscopy image of Ru / NC (b in the figure), it can be seen that the interplanar spacing is 2.14 nm, 2.08 nm, and 1.37 nm, corresponding to the (002), (101), and (110) crystal planes of the metal Ru particles, respectively. The results are consistent with the XRD test results. The catalyst was then subjected to EDS Mapping analysis, and the results are as follows Figure 6 As shown, it can be seen that the N element is successfully doped into the catalyst carrier, and the Ru metal particles are evenly distributed on the surface of the carrier.

[0055] X-ray photoelectron spectroscopy (XPS) was used to characterize the prepared 5Ru / NC-10 (SiO2) to explore the existence form of Ru element on its surface. Figure 7 This is the Ru 3p spectrum. After peak separation, the characteristic peaks at 462.3 eV and 465.2 eV are attributed to Ru 0 3p 3 / 2 and Ru δ+ 3p 3 / 2 orbital, the characteristic peaks at 484.2 eV and 487.1 eV are attributed to Ru 0 3p 1 / 2 Ru δ+ 3p 1 / 2 From the fitted peak area, we can see that the Ru element in the carrier exists in the form of simple substance and oxide, among which Ru 0 Ru δ+ The proportions were 77.0% and 23.0% respectively.

[0056] The prepared 5Ru / NC-10(SiO2) was characterized by CO2-temperature programmed desorption (CO2-TPD) to explore its basicity. Figure 8 CO2 desorption peaks can be seen in the low temperature range (0-200°C), medium-high temperature range (200-400°C), and high temperature range (400-800°C), corresponding to the weak base site, medium-strong base site, and strong base site of the carrier, respectively. It can be seen that the medium-strong base site and strong base site are the main sites in the carrier.

[0057] The prepared 5Ru / NC-10(SiO2) was characterized by NH3-temperature programmed desorption (NH3-TPD) to explore its acidity. Figure 9NH3 desorption peaks can be seen in both the low temperature range (0-200℃) and the medium-high temperature range (200-400℃), corresponding to the weak acid sites and medium-strong acid sites of the carrier, respectively. It can be seen that the weak acid sites and medium-strong acid sites are dominant in the carrier.

[0058] The following are the characterization and Figure 1-9 Basically the same, not provided one by one.

[0059] Example 2: Preparation of 5Ru / NC-5 (SiO2) catalyst

[0060] The preparation of the nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-5 was achieved by a two-step process:

[0061] (1) Preparation of nitrogen-doped carbon support NC-5: Weigh 2 g of glucose (C6H 12 O6), 7 g melamine (C3H6N6), and 1 g silica (SiO2) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-5 carrier.

[0062] (2) Preparation of 5Ru / NC-5 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-5 catalyst.

[0063] Example 3: Preparation of 5Ru / NC-15 (SiO2) catalyst

[0064] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-15 was achieved by a two-step process:

[0065] (1) Preparation of nitrogen-doped carbon support NC-15: Weigh 2 g of glucose (C6H 12O6), 21 g of melamine (C3H6N6), and 1 g of silica (SiO2) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-15 carrier.

[0066] (2) Preparation of 5Ru / NC-15 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-15 catalyst.

[0067] Example 4: Preparation of 5Ru / NC-20 (SiO2) catalyst

[0068] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-20 was achieved by a two-step process:

[0069] (1) Preparation of nitrogen-doped carbon support NC-20: Weigh 2 g of glucose (C6H 12 O6), 28 g of melamine (C3H6N6), and 1 g of silica (SiO2) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-20 carrier.

[0070] (2) Preparation of 5Ru / NC-20 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-20 catalyst.

[0071] The prepared 5Ru / NC-20 (SiO2), 5Ru / NC-20 (Al2O3), 5Ru / NC-20 (K2C2O4), 5Ru / NC-20 (SBA-15), and 5Ru / NC-20 (without pore-forming agent) were characterized by N2-physical adsorption and desorption to explore the effect of different pore-forming agents on the pore structure. The results are shown in Figure 2. Figure 10 and Figure 11 As shown. Figure 10 It can be seen that the adsorption isotherms of all catalysts are typical type IV isotherms, and obvious H4 type hysteresis loops can be observed in the medium relative pressure range (P / P0 = 0.4~1.0), indicating that the support has a mesoporous structure. Figure 11 From the pore size distribution diagram, we can see that the main pore structure of the carrier is mainly mesopores and macropores. The catalyst modified with the pore-forming agent SiO2 has more mesopores and macropores, which is beneficial to the mass transfer of macromolecular lignin, thereby improving the catalytic hydrogenolysis performance, which is consistent with the experimental results.

[0072] Example 5: Preparation of 5Ru / NC-25 (SiO2) catalyst

[0073] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-25 was achieved by a two-step process:

[0074] (1) Preparation of nitrogen-doped carbon support NC-25: Weigh 2 g of glucose (C6H 12 O6), 35 g of melamine (C3H6N6), and 1 g of silica (SiO2) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-25 carrier.

[0075] (2) Preparation of 5Ru / NC-25 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-25 catalyst.

[0076] Example 6: Preparation of 5Ru / NC-20 (Al2O3) catalyst

[0077] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-20 was achieved by a two-step process:

[0078] (1) Preparation of nitrogen-doped carbon support NC-20: Weigh 2 g of glucose (C6H 12 O6), 28 g of melamine (C3H6N6), and 1 g of alumina (Al2O3) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-20 support.

[0079] (2) Preparation of 5Ru / NC-20 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-20 catalyst.

[0080] Example 7: Preparation of 5Ru / NC-20 (K2C2O4) catalyst

[0081] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-20 was achieved by a two-step process:

[0082] (1) Preparation of nitrogen-doped carbon support NC-20: Weigh 2 g of glucose (C6H 12 O6), 28 g of melamine (C3H6N6), and 1 g of potassium oxalate (K2C2O4) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground, acid-washed with 2 mol / L HCl solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-20 support.

[0083] (2) Preparation of 5Ru / NC-20 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-20 catalyst.

[0084] Example 8: Preparation of 5Ru / NC-20 (SBA-15) catalyst

[0085] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-20 was achieved by a two-step process:

[0086] (1) Preparation of nitrogen-doped carbon support NC-20: Weigh 2 g of glucose (C6H 12 O6), 28 g of melamine (C3H6N6), and 1 g of mesoporous molecular sieve (SBA-15) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60°C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground and alkaline washed with 2 mol / L NaOH solution for 12 h, filtered, washed with deionized water until neutral, and dried at 80°C to obtain a black solid, which is the NC-20 support.

[0087] (2) Preparation of 5Ru / NC-20 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-20 catalyst.

[0088] Example 9: Preparation of 5Ru / NC-20 (without pore former) catalyst

[0089] The preparation of nitrogen-doped carbon-supported ruthenium catalyst 5Ru / NC-20 was achieved by a two-step process:

[0090] (1) Preparation of nitrogen-doped carbon support NC-20: Weigh 2 g of glucose (C6H 12O6), 28 g of melamine (C3H6N6) were stirred and mixed in 80 mL of deionized water solution, rotary evaporated at 60 ° C, dried overnight, placed in a quartz boat, and calcined under a nitrogen atmosphere. The obtained solid was ground to obtain a black solid, which is the NC-20 carrier.

[0091] (2) Preparation of 5Ru / NC-20 catalyst: Weigh 0.0639 g of ruthenium acetylacetonate (C 15 H 21 O6Ru) solid was dissolved in N,N-dimethylformamide (DMF), and the solution was dripped into a Petri dish containing 0.3 g of the carrier, stirred continuously, and allowed to stand at room temperature for 12 h. The mixture was then dried in an oven at 80°C. After drying, the sample was ground into powder and placed in a vertical tube furnace with a H2 flow rate of 10 mL·min -1 , and reduced at 350 °C for 4 h to obtain 5Ru / NC-20 catalyst.

[0092] Example 10: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0093] (1) Lignin extraction: Weigh 10 g of sugarcane bagasse raw material and 120 mL of extract, add them to a 250 mL hydrothermal kettle, and place it in an oven at 110°C for 4 h. After cooling to room temperature, filter it and rinse it with ethanol. Collect the filtrate and washing liquid, and add 500 mL of deionized water to precipitate the lignin. After filtering through a filter membrane, place it in a fume hood and air dry it naturally. Grind it into powder, which is the organic-soluble bagasse lignin. The extract is composed of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0094] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble bagasse lignin extracted in step (1), 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, and the air in the reactor was replaced three times with high-purity hydrogen. Then, 2 MPa of hydrogen was filled in and the reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed, and internal standard dimethyl phthalate was added. After mixing evenly, 1 mL of the reaction solution was taken for analysis by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. The regenerated lignin was obtained after filtration and drying.

[0095] The samples were analyzed by gas chromatography-mass spectrometry (HP-INNOWAX column: 30 m × 0.25 mm × 0.25 μm, column flow rate 2 mL min -1, split ratio 20:1. Heating program: 50℃ for 1 min, then 10℃ min -1 The product was qualitatively analyzed and quantitatively calculated by heating at a rate of 280°C and maintaining for 15 min. The GC-FID results of the product are shown in Figure 2. Figure 10 and as shown in Table 1.

[0096] Calculation results show that, under the catalytic action of the 5Ru / NC-10 catalyst, the conversion of lignin reached 89.50%, with a total product yield of 33.22%, including 27.20% of phenolic products. Among all products, those containing G and S units were more abundant, indicating that the catalyst system has good reactivity towards G and S structural units.

[0097] Table 1 Identification and yield of volatile products

[0098] Example 11: 5Ru / NC-5 (SiO2) catalyzed depolymerization of lignin

[0099] The difference between this embodiment and embodiment 10 is that:

[0100] 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-5 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, and the air inside was replaced three times with high-purity hydrogen. The reactor was then filled with 2 MPa of hydrogen and allowed to react at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was then analyzed by GC-MS-FID.

[0101] The calculation results show that the conversion rate of lignin is 95.70%, the total yield of products is 26.76%, of which the total yield of phenolic products is 16.81%.

[0102] Example 12: 5Ru / NC-15 (SiO2) catalyzed depolymerization of lignin

[0103] The difference between this embodiment and embodiment 10 is that:

[0104] 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-15 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, and the air inside was replaced three times with high-purity hydrogen. The reactor was then filled with 2 MPa of hydrogen and allowed to react at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was then analyzed by GC-MS-FID.

[0105] The calculation results show that the conversion rate of lignin is 87.46%, the total yield of products is 27.38%, and the total yield of phenolic products is 22.87%.

[0106] Example 13: 5Ru / NC-20 (SiO2) catalyzed depolymerization of lignin

[0107] The difference between this embodiment and embodiment 10 is that:

[0108] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-20 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0109] The calculation results show that the conversion rate of lignin is 85.06%, the total yield of products is 23.94%, of which the total yield of phenolic products is 12.64%.

[0110] Example 14: 5Ru / NC-20 (Al2O3) catalyzed lignin depolymerization

[0111] The difference between this embodiment and embodiment 13 is that:

[0112] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-20 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0113] The calculation results show that the conversion rate of lignin is 90.57%, the total yield of products is 19.95%, of which the total yield of phenolic products is 14.15%.

[0114] Example 15: 5Ru / NC-20 (K2C2O4) catalyzed lignin depolymerization

[0115] The difference between this embodiment and embodiment 13 is that:

[0116] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-20 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0117] The calculation results show that the conversion rate of lignin is 82.04%, the total yield of products is 18.19%, and the total yield of phenolic products is 15.46%.

[0118] Example 16: 5Ru / NC-20 (SBA-15) catalyzed depolymerization of lignin

[0119] The difference between this embodiment and embodiment 13 is that:

[0120] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-20 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0121] The calculation results show that the conversion rate of lignin is 84.12%, the total yield of products is 23.89%, and the total yield of phenolic products is 19.08%.

[0122] Example 17: 5Ru / NC-10 (600°C) catalytic depolymerization of lignin

[0123] The difference between this embodiment and embodiment 10 is that:

[0124] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0125] The calculation results show that the conversion rate of lignin is 80.90%, the total yield of products is 20.06%, and the total yield of phenolic products is 15.63%.

[0126] Example 18: 5Ru / NC-10 (1000°C) catalytic depolymerization of lignin

[0127] The difference between this embodiment and embodiment 10 is that:

[0128] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0129] The calculation results show that the conversion rate of lignin is 87.03%, the total yield of products is 19.87%, and the total yield of phenolic products is 13.48%.

[0130] Example 19: 1Ru / NC-10 (SiO2) catalyzed lignin depolymerization

[0131] The difference between this embodiment and embodiment 10 is that:

[0132] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 1Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0133] The calculation results show that the conversion rate of lignin is 92.00%, the total yield of products is 18.28%, and the total yield of phenolic products is 15.92%.

[0134] Example 20: 3Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0135] The difference between this embodiment and embodiment 10 is that:

[0136] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 3Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0137] The calculation results show that the conversion rate of lignin is 91.99%, the total yield of products is 24.22%, and the total yield of phenolic products is 20.00%.

[0138] Example 21: 7Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0139] The difference between this embodiment and embodiment 10 is that:

[0140] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 7Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0141] The calculation results show that the conversion rate of lignin is 89.72%, the total yield of products is 24.32%, and the total yield of phenolic products is 19.98%.

[0142] Example 22: 9Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0143] The difference between this embodiment and embodiment 10 is that:

[0144] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 9Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0145] The calculation results show that the conversion rate of lignin is 92.68%, the total yield of products is 22.29%, of which the total yield of phenolic products is 12.29% and the yield of saturated products is 9.38%.

[0146] Example 23: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0147] The difference between this embodiment and embodiment 10 is that:

[0148] Weigh 100 mg of organosoluble bagasse lignin, 50 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0149] The calculation results show that the conversion rate of lignin is 90.15%, the total yield of products is 27.00%, and the total yield of phenolic products is 20.38%.

[0150] Example 24: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0151] The difference between this embodiment and embodiment 10 is that:

[0152] 100 mg of organosoluble bagasse lignin, 75 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, and the air inside was replaced three times with high-purity hydrogen. The reactor was then filled with 2 MPa of hydrogen and allowed to react at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was then analyzed by GC-MS-FID.

[0153] The calculation results show that the conversion rate of lignin is 89.73%, the total yield of products is 30.25%, and the total yield of phenolic products is 22.19%.

[0154] Example 25: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0155] The difference between this embodiment and embodiment 10 is that:

[0156] Weigh 100 mg of organosoluble bagasse lignin, 125 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air three times with high-purity hydrogen, and then fill it with 2 MPa of hydrogen. The reaction was carried out at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0157] The calculation results show that the conversion rate of lignin is 88.75%, the total yield of products is 31.14%, of which the total yield of phenolic products is 14.06%.

[0158] Example 26: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0159] The difference between this embodiment and embodiment 10 is that:

[0160] 100 mg of organosoluble bagasse lignin, 150 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed sequentially into a 50 mL reactor. The reactor was sealed, the air in the reactor was replaced three times with high-purity hydrogen, and then filled with 2 MPa of hydrogen. The reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0161] The calculation results show that the conversion rate of lignin is 88.62%, the total yield of products is 29.61%, and the total yield of phenolic products is 18.01%.

[0162] Example 27: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0163] The difference between this embodiment and embodiment 10 is that:

[0164] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 240°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0165] The calculation results show that the conversion rate of lignin is 88.70%, the total yield of products is 25.57%, and the total yield of phenolic products is 17.88%.

[0166] Example 28: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0167] The difference between this embodiment and embodiment 10 is that:

[0168] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 250°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0169] The calculation results show that the conversion rate of lignin is 89.13%, the total yield of products is 30.43%, and the total yield of phenolic products is 21.52%.

[0170] Example 29: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0171] The difference between this embodiment and embodiment 10 is that:

[0172] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 270°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0173] The calculation results show that the conversion rate of lignin is 90.24%, the total yield of products is 29.64%, of which the total yield of phenolic products is 19.51%.

[0174] Example 30: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0175] The difference between this embodiment and embodiment 10 is that:

[0176] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 280°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0177] The calculation results show that the conversion rate of lignin is 92.03%, the total yield of products is 30.04%, of which the total yield of phenolic products is 17.4%.

[0178] Example 31: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0179] The difference between this embodiment and embodiment 10 is that:

[0180] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 1 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0181] The calculation results show that the conversion rate of lignin is 85.43%, the total yield of products is 28.91%, and the total yield of phenolic products is 23.88%.

[0182] Example 32: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0183] The difference between this embodiment and embodiment 10 is that:

[0184] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air three times with high-purity hydrogen, then fill with 1.5 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0185] The calculation results show that the conversion rate of lignin is 87.25%, the total yield of products is 29.10%, and the total yield of phenolic products is 24.20%.

[0186] Example 33: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0187] The difference between this embodiment and embodiment 10 is that:

[0188] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2.5 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0189] The calculation results show that the conversion rate of lignin is 89.14%, the total yield of products is 31.85%, and the total yield of phenolic products is 20.47%.

[0190] Example 34: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0191] The difference between this embodiment and embodiment 10 is that:

[0192] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 3 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0193] The calculation results show that the conversion rate of lignin is 90.74%, the total yield of products is 30.48%, and the total yield of phenolic products is 14.87%.

[0194] Example 35: 5Ru / NC-10 (SiO2) catalyzed lignin depolymerization

[0195] The difference between this embodiment and embodiment 10 is that:

[0196] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 2 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0197] The calculation results show that the conversion rate of lignin is 88.64%, the total yield of products is 27.25%, and the total yield of phenolic products is 20.93%.

[0198] Example 36: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0199] The difference between this embodiment and embodiment 10 is that:

[0200] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air three times with high-purity hydrogen, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 3 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0201] The calculation results show that the conversion rate of lignin is 89.92%, the total yield of products is 29.94%, and the total yield of phenolic products is 21.31%.

[0202] Example 37: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0203] The difference between this embodiment and embodiment 10 is that:

[0204] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air three times with high-purity hydrogen, and then fill it with 2 MPa of hydrogen. The reaction was then carried out at 260°C for 5 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0205] The calculation results show that the conversion rate of lignin is 91.32%, the total yield of products is 29.65%, of which the total yield of phenolic products is 18.23%.

[0206] Example 38: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0207] The difference between this embodiment and embodiment 10 is that:

[0208] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 6 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate (an internal standard). 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0209] The calculation results show that the conversion rate of lignin is 90.73%, the total yield of products is 30.96%, of which the total yield of phenolic products is 16.66%.

[0210] Example 39: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0211] The difference between this embodiment and embodiment 10 is that:

[0212] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of methanol into a 50 mL reactor. Seal the reactor, replace the air with high-purity hydrogen three times, then fill with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0213] The calculation results show that the conversion rate of lignin is 84.91%, the total yield of products is 32.47%, and the total yield of phenolic products is 18.68%.

[0214] Example 40: 5Ru / NC-10 (SiO2) catalyzed lignin depolymerization

[0215] The difference between this embodiment and embodiment 10 is that:

[0216] Weigh 100 mg of organosoluble bagasse lignin, 100 mg of 5Ru / NC-10 catalyst, and 20 mL of ethanol into a 50 mL reactor. Seal the reactor, replace the air in the reactor with high-purity hydrogen three times, then fill it with 2 MPa of hydrogen. Reaction was continued at 260°C for 4 h. After the reaction was complete and cooled to room temperature, the reaction solution was removed and added with dimethyl phthalate as an internal standard. 1 mL of the reaction solution was analyzed by GC-MS-FID.

[0217] The calculation results show that the conversion rate of lignin is 85.29%, the total yield of products is 30.47%, of which the total yield of phenolic products is 18.07%.

[0218] Example 41: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0219] The difference between this embodiment and embodiment 10 is that:

[0220] (1) Lignin extraction: Weigh 10 g of bamboo raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal kettle, and place them in an oven at 110°C for 4 h. After cooling to room temperature, filter and rinse with ethanol. Collect the filtrate and washing liquid, and add 500 mL of deionized water to precipitate lignin. After filtering through a filter membrane, place it in a fume hood and air dry naturally. Grind it into powder, which is the organic-soluble bamboo lignin. The extract solution consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0221] (2) Catalytic depolymerization of lignin: 100 mg of the organically dissolved bamboo lignin extracted in step (1), 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, and the air in the reactor was replaced three times with high-purity hydrogen. 2 MPa of hydrogen was then added, and the reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed, and internal standard dimethyl phthalate was added. After mixing evenly, 1 mL of the reaction solution was taken for analysis by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. The regenerated lignin was obtained after filtration and drying.

[0222] The calculation results show that the conversion rate of lignin is 85.83%, the total yield of products is 22.48%, and the total yield of phenolic products is 19.36%.

[0223] Example 42: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0224] The difference between this embodiment and embodiment 10 is that:

[0225] (1) Lignin extraction: Weigh 10 g of rice straw raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal autoclave, and place them in an oven at 110°C for 4 h. After cooling to room temperature, filter and rinse with ethanol. Collect the filtrate and washing liquid, and add 500 mL of deionized water to precipitate the lignin. After filtering through a filter membrane, place it in a fume hood and air dry it naturally. Grind it into powder, which is the organic-soluble rice straw lignin. The extract solution is composed of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0226] (2) Catalytic depolymerization of lignin: 100 mg of the organically soluble rice straw lignin extracted in step (1), 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, and the air in the reactor was replaced with high-purity hydrogen three times. Then, 2 MPa of hydrogen was filled in and the reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed, and internal standard dimethyl phthalate was added. After mixing evenly, 1 mL of the reaction solution was taken for analysis by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The filtrate was allowed to stand for about 24 h to precipitate the unreacted lignin. After filtration and drying, the regenerated lignin was obtained.

[0227] The calculation results show that the conversion rate of lignin is 75.31%, the total yield of products is 9.12%, and the total yield of phenolic products is 7.39%.

[0228] Example 43: 5Ru / NC-10 (SiO2) catalyzed lignin depolymerization

[0229] The difference between this embodiment and embodiment 10 is that:

[0230] (1) Lignin extraction: Weigh 10 g corncob raw material and 120 mL of extract solution, add them to a 250 mL hydrothermal autoclave, and place in an oven at 110°C for 4 h. After cooling to room temperature, filter and rinse with ethanol. Collect the filtrate and washing liquid, and add 500 mL of deionized water to precipitate lignin. After filtering through a filter membrane, place it in a fume hood and air dry naturally. Grind it into powder, which is the organic-soluble corncob lignin. The extract solution is composed of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0231] (2) Catalytic depolymerization of lignin: 100 mg of the organic-soluble corncob lignin extracted in step (1), 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, and the air in the reactor was replaced with high-purity hydrogen three times. Then, 2 MPa of hydrogen was filled in and the reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed, and internal standard dimethyl phthalate was added. After mixing evenly, 1 mL of the reaction solution was taken for analysis by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. The regenerated lignin was obtained after filtration and drying.

[0232] The calculation results show that the conversion rate of lignin is 78.23%, the total yield of products is 12.27%, and the total yield of phenolic products is 8.40%.

[0233] Example 44: 5Ru / NC-10 (SiO2) catalyzed depolymerization of lignin

[0234] The difference between this embodiment and embodiment 10 is that:

[0235] (1) Lignin extraction: Weigh 10 g of poplar wood raw material and 120 mL of extract, add them to a 250 mL hydrothermal kettle, and place them in an oven at 110°C for 4 h. After cooling to room temperature, filter and rinse with ethanol. Collect the filtrate and washing liquid, and add 500 mL of deionized water to precipitate lignin. After filtering through a filter membrane, place it in a fume hood and air dry naturally. Grind it into powder, which is the organic-soluble poplar wood lignin. The extract consists of 24 g of 98% concentrated sulfuric acid, 3200 mL of anhydrous ethanol, and 800 mL of deionized water.

[0236] (2) Catalytic depolymerization of lignin: 100 mg of the organically soluble poplar lignin extracted in step (1), 100 mg of 5Ru / NC-10 catalyst, and 20 mL of isopropanol were weighed in a 50 mL reactor. The reactor was sealed, and the air in the reactor was replaced three times with high-purity hydrogen. 2 MPa of hydrogen was then added, and the reaction was carried out at 260°C for 4 h. After the reaction was completed and cooled to room temperature, the reaction solution was removed, and internal standard dimethyl phthalate was added. After mixing evenly, 1 mL of the reaction solution was taken for analysis by GC-MS-FID. The reaction solution was filtered to obtain a filtrate, and deionized water was added to 200 mL. The solution was allowed to stand for about 24 h to precipitate the unreacted lignin. The regenerated lignin was obtained after filtration and drying.

[0237] The calculation results show that the conversion rate of lignin is 89.92%, the total yield of products is 24.84%, and the total yield of phenolic products is 21.89%.

[0238] As can be seen from the above examples, the present invention utilizes a nitrogen-doped carbon-supported ruthenium catalyst system to achieve selective hydrogenolysis of lignin. Under conditions of H₂ pressure of 1–3 MPa, reaction temperature of 240–280°C, and reaction time of 2–6 h, the lignin conversion rate reached 80.90%–95.70%, and the total product yield was 18.19%–33.22%, with the total yield of phenolic products reaching 14.06%–27.23%. The nitrogen-doped carbon-supported ruthenium catalyst employed in the present invention offers relatively low cost among precious metal catalysts, a simple preparation process, and minimal environmental impact, enabling lignin depolymerization under mild conditions.

[0239] Example 45: Recyclability of catalyst

[0240] Taking the reuse of a 5Ru / NC-10 (SiO2) catalyst as an example, the reuse process is as follows: After the reaction, the catalyst is filtered and separated, placed in a tetrahydrofuran (THF) solution, stirred at room temperature for 12 hours, filtered, and oven-dried at 80°C. The resulting catalyst solid is then recycled according to the steps in Example 9. Tests show that the catalyst activity does not decrease significantly after five cycles, with a lignin conversion rate of 86.71% and a total product yield of 31.61%, including a total yield of phenolic products of 21.18%.

[0241] As can be seen from the above examples, the modified nitrogen-doped carbon-loaded ruthenium catalytic system of the present invention is combined with alcohol solvents to achieve selective hydrogenolysis of lignin. Under the conditions of ruthenium loading of 1~9 wt.%, nitrogen doping amount of 5~25 mol.%, H2 pressure of 1~3 MPa, reaction temperature of 240~280°C, and reaction time of 2~6 h, the conversion rate of lignin is 80.90%~95.70%, and the total yield of product is 18.19%~33.22%, of which the total yield of phenolic products is 14.06%~27.23%. The technology used in the present invention has the characteristics of renewable raw materials, simple reaction process, mild reaction conditions, and environmentally friendly catalyst, mainly having the following characteristics:

[0242] 1) Compared with traditional carbon-supported metal-loaded catalysts, the catalyst of the present invention nitrogen-dopes the carbon material. The nitrogen doping and the defects of the carbon material provide additional anchor points for the metal atoms, which can promote the dispersion of metallic ruthenium. At the same time, the nitrogen doping can provide more basic sites for the catalyst. The active metallic ruthenium is loaded after the support is prepared, which avoids the phenomenon of metal coating during the one-step pyrolysis preparation, improves the performance of lignin hydrogenolysis, and achieves the selective depolymerization of lignin.

[0243] 2) A pore-forming agent was added during the preparation of the catalyst to prepare a porous catalyst, which resulted in more mesoporous structures in the catalyst, which was beneficial to the mass transfer of macromolecular lignin.

[0244] 3) Nitrogen-doped carbon supports enhance the interaction between the metal and the support, improving the activity and stability of the catalyst. After five cycles, the catalyst activity showed no significant decrease, indicating the catalyst's good stability.

[0245] Overall, the nitrogen-doped carbon support in the present invention effectively regulates the acidity and electronic structure of the catalyst during lignin hydrogenolysis, thereby improving the catalyst's performance in hydrogenolysis of lignin. Under mild reaction conditions, higher overall product yields and phenolic bioproduct yields are achieved. Furthermore, the catalyst of the present invention exhibits excellent substrate compatibility with lignin from diverse biomass sources, enabling efficient catalytic hydrogenolysis of lignin from sources such as bagasse, bamboo, and poplar.

[0246] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be considered as equivalent replacement methods and shall be included in the scope of protection of the present invention.

Claims

1. A method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst, characterized in that: An organic soluble lignin, a modified nitrogen-doped carbon support-supported ruthenium catalyst, and a short-chain monohydric alcohol are mixed and reacted at a hydrogen pressure of 1 to 3 MPa and a temperature of 240 to 280°C for 2 to 6 hours to obtain a monophenol product. The modified nitrogen-doped carbon support-supported ruthenium catalyst comprises an NC-X support prepared using glucose as a carbon source, melamine as a nitrogen source, and one of SiO2, Al2O3, K2C2O4, and SBA-15 as a pore-forming agent; and an active component, ruthenium, wherein the ruthenium loading amount is 1 to 9 wt.%; and X in the support NC-X represents the molar ratio of N / C, which is 5 to 25.

2. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 1, wherein: The preparation method of the modified nitrogen-doped carbon support-supported ruthenium catalyst is as follows: fully dissolving a ruthenium source in a solvent, adding an NC-X support for impregnation, standing for 10 to 14 hours, drying, and then reducing it under a H2 atmosphere to obtain a Ru / NC catalyst.

3. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claims 1 and 2, characterized in that: Glucose, melamine and a pore-forming agent are fully mixed in a deionized water solution to form a mixed solution, which is then dried, calcined under a nitrogen atmosphere, alkali washed, and washed with water until neutral to obtain an NC-X carrier.

4. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 3, wherein: The calcination method is carried out in a tubular furnace, the calcination temperature is 600-1000°C, the heating rate is 2-3°C / min, and the calcination time is 1-2 hours; the mixed solution is 1-3 g of glucose, 7-35 g of melamine, and 0.5-1.5 g of a pore-forming agent added to every 80 mL of deionized water solution; the alkali washing refers to alkali washing the catalyst with a sodium hydroxide solution to wash away the pore-forming agent.

5. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 2, wherein: The ruthenium source is one of ruthenium acetylacetonate and hydrated ruthenium trichloride; and the solvent is one of N,N-dimethylformamide, dichloromethane and acetone.

6. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 2, wherein: The reduction under H2 atmosphere is carried out in a vertical tube furnace, the reduction temperature is 300-400°C, and the reduction time is 3-5 hours.

7. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 1, wherein: The mass ratio of the organic lignin to the Ru / NC catalyst modified by the pore-forming agent is 1:0.5-1:1.

5.

8. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 1, wherein: The short-chain monohydric alcohol is one of isopropanol, ethanol and methanol.

9. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 1, wherein: The organic soluble lignin is extracted by the following method: adding the lignin raw material and the extract into a reactor, reacting at 100-120°C for 2-6 hours, and then filtering and separating; adding deionized water to the obtained filtrate, filtering to obtain a solid, and drying to obtain the organic soluble lignin; the extract is composed of a mixture of concentrated sulfuric acid, anhydrous ethanol and deionized water, wherein the mass concentration of the concentrated sulfuric acid is 95-98%, and 3200-4000 mL of anhydrous ethanol and 800-1000 mL of deionized water are added to every 24 g of concentrated sulfuric acid; and 120-150 mL of the extract is added to every 10 g of the lignin raw material.

10. The method for catalyzing the hydrogenolysis of lignin using a modified nitrogen-doped carbon support-supported ruthenium catalyst according to claim 9, wherein: The lignin raw material is derived from any one of bagasse, bamboo, straw, poplar and corn cob; the phenolic product is one or more of 4-propyl eugenol, 4-ethyl eugenol, 4-propyl guaiacol, 4-ethyl guaiacol and 4-ethylphenol.

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