Vanadium salt and carbon-based composite lignin depolymerization catalyst and application thereof
By leveraging the synergistic effect of vanadium salt and carbon-based composite catalysts, the problems of difficult catalyst separation and low efficiency in existing technologies have been solved, achieving highly efficient oxidative depolymerization of lignin C-bonds. The catalyst is easy to separate and its catalytic efficiency is significantly improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN AGRI UNIV
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-05
AI Technical Summary
Existing homogeneous catalysts are difficult to separate, while heterogeneous catalysts have low catalytic efficiency, making it difficult to achieve high yields of lignin C-C bond oxidation and depolymerization.
A vanadium salt and carbon-based composite lignin depolymerization catalyst is adopted, which is a mixture of vanadium salt and carbon-based materials with a mass ratio of vanadium salt to carbon-based material of 3.7~12.5:40. Through the interfacial interaction between the active center of vanadium salt and carbon-based material, synergistic catalysis is achieved, realizing the high activity of homogeneous catalysis and the structural advantages of heterogeneous catalysis.
The catalyst exhibits high catalytic efficiency and is easy to separate. The vanadium salt and carbon-based composite catalyst shows a significant synergistic catalytic effect in lignin model compounds, with a conversion rate of 52% to 100% for 2-phenoxy-1-phenylethanol, a yield of 32% to 68% for phenol, and a yield of 31% to 77% for methyl benzoate.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lignin depolymerization catalyst technology, specifically relating to a vanadium salt and carbon-based composite lignin depolymerization catalyst and its application. Background Technology
[0002] Biomass is abundant and has low carbon emissions, making it a clean energy source. Among various biomass energy sources, lignocellulosic biomass is the most widely distributed and abundant. Lignin is the second most abundant component of lignocellulosic biomass after cellulose. As the only renewable source of aromatic compounds in nature, lignin has unique advantages in converting into high-value-added oxygenated aromatic compounds and other bulk chemicals.
[0003] Lignin is composed of numerous aromatic structural units interconnected by CO and C-C bonds. Catalytic oxidation can selectively break these C-C bonds, utilizing the oxygen-containing groups and aromatic structures inherent in lignin to obtain aromatic compounds with oxygen-containing functional groups. The core of this oxidative depolymerization lies in developing catalysts capable of efficiently cleaving these chemical bonds. Currently, most homogeneous catalysts are metal complexes, which are difficult to separate after the reaction. Heterogeneous catalytic systems generally have low catalytic efficiency, making it difficult to achieve high yields. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a vanadium salt and carbon-based composite lignin depolymerization catalyst and its application.
[0005] The first objective of this invention is to provide a vanadium salt and carbon-based composite lignin depolymerization catalyst, which is composed of a mixture of vanadium salt and carbon-based materials.
[0006] The mass ratio of vanadium salt to carbon-based salt is 3.7~12.5:40.
[0007] The vanadium salt is any one of vanadium acetylacetonate, vanadium acetylacetonate oxyacetate, vanadium oxysulfate, vanadium oxalate, vanadium triisopropanol oxyacetate, and ammonium metavanadate.
[0008] The carbon base is biochar or activated carbon.
[0009] Preferably, the biochar is prepared by pyrolysis of wheat straw, rice straw, corn straw or rapeseed straw at 300℃~600℃.
[0010] Preferably, the method for preparing the biochar includes the following steps: 1) Air dry the straw, crush it, and pass it through a 50-mesh sieve to obtain straw pellets.
[0011] 2) Take 10g of straw pellets and place them in a tube furnace for inert roasting under a nitrogen atmosphere. The heating rate is 2℃ / min~25℃ / min, the roasting temperature is 200℃~1000℃, and the roasting time is 1h~6h. After roasting, pass the pellets through a 200-mesh sieve to obtain biochar.
[0012] Preferably, the straw is one of wheat straw, rice straw, corn straw, or rapeseed straw. Preferably, the heating rate is 5℃ / min~10℃ / min, the calcination temperature is 300℃~600℃, and the calcination time is 2h~4h.
[0013] Preferably, the activated carbon is one or more of coal-based activated carbon, wood-based activated carbon, and fruit shell activated carbon.
[0014] A second objective of this invention is to provide an application of a vanadium salt and carbon-based composite lignin depolymerization catalyst, comprising the following steps: Vanadium salt and carbon-based composite lignin depolymerization catalyst, solvent and lignin are added to a reaction vessel, sealed and stirred. The air in the reaction vessel is replaced with oxygen, and oxygen is added to a pressure of 0.1 MPa to 1 MPa. The reaction is carried out at 80℃ to 180℃ for 2 to 24 hours, and then cooled to obtain oxygen-containing aromatic compounds.
[0015] Preferably, the mass ratio of the vanadium salt and carbon-based composite lignin depolymerization catalyst, solvent and lignin is 43.7~52.5:42.8:4000.
[0016] Preferably, the oxygen pressure is 0.5 MPa.
[0017] Preferably, the reaction temperature is 100℃~180℃ and the time is 4h~24h.
[0018] Preferably, the reaction temperature is 140°C.
[0019] Preferably, the stirring speed is 700 rpm.
[0020] Preferably, the solvent is any one of methanol, ethanol, isopropanol, water, N,N-dimethylformamide, and dimethyl sulfoxide.
[0021] Preferably, the lignin is a β-O-4 model compound.
[0022] The oxygen-containing aromatic compound is one or more of phenol, benzoic acid, methyl benzoylformate, methyl benzoate, methyl 3,4-dimethylbenzoate, and methyl anisinate.
[0023] Preferably, the β-O-4 model compound is 2-phenoxy-1-phenylethanol, 2-(4-methoxyphenoxy)-1-phenylethanol, 2-(3,4-dimethoxyphenoxy)-1-phenylethanol, 2-phenoxy-1-(4-methoxyphenyl)ethanol, 2-(4-methoxyphenoxy)-1-(4-methoxyphenyl)ethanol, or 2-phenoxy-1-(3,4-dimethoxyphenyl)ethanol.
[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. The vanadium salt and carbon-based composite lignin depolymerization catalyst of the present invention comprises vanadium salt and carbon-based material. The mass ratio of vanadium salt to carbon-based material is 3.7~12.5:40. The vanadium salt is any one of vanadium acetylacetonate, vanadium oxyacetylacetonate, vanadium oxysulfate, vanadium oxyoxalate, vanadium triisopropanol oxyvanadium, and ammonium metavanadate. The carbon-based material is biochar or activated carbon. The present invention achieves both the high activity characteristics of homogeneous catalysis and the structural advantages of heterogeneous catalysis through the synergistic interfacial interaction between the active center of the vanadium salt and the carbon-based material, resulting in high catalytic efficiency. The vanadium salt and carbon-based composite lignin depolymerization catalyst of the present invention uses only two raw materials: vanadium salt and carbon-based material, which are simply mixed in a specific ratio to obtain the catalyst. Therefore, the raw material composition is simple, and the preparation and operation methods are straightforward. Furthermore, in the vanadium salt and carbon-based composite lignin depolymerization catalyst of the present invention, the vanadium salt and carbon-based material are solids and easily separated from the reaction system. Therefore, the vanadium salt and carbon-based composite lignin depolymerization catalyst of the present invention not only has high catalytic activity but also has the advantages of simple preparation and easy separation from the reaction system.
[0025] On the other hand, vanadium salts are non-noble metal catalysts, exhibiting advantages in the C / C bond cleavage of specific substrates. The carbon-based component is activated carbon. Carbon-based materials are highly efficient synergistic catalytic components, not only promoting the dispersion of active components through high specific surface area and regulating electron transfer via heteroatoms or defect sites, but also enhancing the redox cycle of metal ions and stabilizing reaction intermediates. This invention constructs a carbon-based material-vanadium salt synergistic catalytic system to achieve efficient selective oxidative cleavage of lignin C / C bonds, yielding oxygen-containing aromatic compounds.
[0026] The vanadium salt and activated carbon composite system of this invention exhibits a significant synergistic catalytic effect in the catalytic depolymerization of lignin model compounds, while each component exhibits weak catalytic activity when acting alone. When the two form a composite catalytic system, they can effectively promote the conversion of the substrate and the selective formation of the target product, with catalytic efficiency far exceeding that of the simple superposition of single components. The lignin depolymerization catalyst prepared by the synergistic effect of vanadium salt and activated carbon of this invention, under the conditions of oxidative catalysis using the lignin model compound 2-phenoxy-1-phenylethanol as the substrate, methanol as the solvent, temperature 140℃, and oxygen pressure 0.5 MPa, achieves a conversion rate of 52%–100% for 2-phenoxy-1-phenylethanol, a phenol yield of 32%–68%, and a methyl benzoate yield of 31%–77%. Among these, the catalyst combination of activated carbon and V(acac)3 in Example 7 shows the best effect, achieving a 100% conversion rate of 2-phenoxy-1-phenylethanol, a 68% phenol yield, and a 77% methyl benzoate yield. The results of Comparative Examples 1 to 7 show that vanadium salts or activated carbon alone have low efficiency in catalytic oxidation and depolymerization of lignin. Except for Comparative Example 2, which reaches 35%, and Comparative Example 4, which reaches 63%, the efficiency of the other comparative examples is below 20%. Among the product yields of the comparative examples, the yield of phenol is below 20%, and the yield of methyl benzoate is below 15%. The results of Comparative Example 1 show that activated carbon alone has low catalytic oxidation and depolymerization activity for lignin, with a conversion rate of 10% for 2-phenoxy-1-phenylethanol, a yield of 2% for phenol, and a yield of 5% for methyl benzoate.
[0027] In summary, the vanadium salt and carbon-based lignin depolymerization catalyst of the present invention has high catalytic activity for lignin depolymerization, and is simple to prepare and easy to separate from the reaction system. Detailed Implementation
[0028] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the following detailed description, in conjunction with preferred embodiments, provides a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0029] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.
[0030] I. Experimental Materials The activated carbon used in this invention was purchased from Zhengzhou Niute Agricultural Technology Co., Ltd., with a particle size of 200 mesh, and belongs to the category of fruit shell activated carbon.
[0031] The straw biochar used in this invention is prepared by pyrolysis of wheat straw, rice straw, corn straw, or rapeseed straw at 300℃ to 600℃. For example, 500℃ rice straw biochar is prepared by pyrolysis of rice straw at 500℃, and 300℃ wheat straw biochar is prepared by pyrolysis of wheat straw at 300℃.
[0032] II. Experimental Methods The method for calculating the substrate conversion rate in this invention is shown in formula (1), and the method for calculating the product yield is shown in formula (2): Formula (1): ; Formula (2): Production .
[0033] In the formula, n1 is the amount of the model compound before the catalytic reaction. ni is the amount of the product. n2 is the amount of the remaining substrate.
[0034] Example 1 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.0037 g of ammonium metavanadate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 4 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 66%, the phenol yield was 43%, and the methyl benzoate yield was 36%.
[0035] Example 2 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.00837 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.1 MPa. The temperature was raised to 80 °C, and the reaction was carried out for 2 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 73%, the phenol yield was 54%, and the methyl benzoate yield was 43%.
[0036] Example 3 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.00515 g of vanadium oxysulfate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 1 MPa. The temperature was raised to 180 °C, and the reaction was carried out for 24 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 65%, the phenol yield was 35%, and the methyl benzoate yield was 30%.
[0037] Example 4 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.0110 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 82%, the phenol yield was 58%, and the methyl benzoate yield was 47%.
[0038] Example 5 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.0049 g of vanadium oxalate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 59%, the phenol yield was 39%, and the methyl benzoate yield was 33%.
[0039] Example 6 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.0077 g of triisopropanol vanadium oxide, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 75%, the phenol yield was 49%, and the methyl benzoate yield was 42%.
[0040] Example 7 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 100%, the phenol yield was 68%, and the methyl benzoate yield was 77%.
[0041] Example 8 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of wheat straw biochar (300℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 95%, the phenol yield was 57%, and the methyl benzoate yield was 56%.
[0042] Example 9 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of wheat straw biochar (400℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃ and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 94%, the phenol yield was 52%, and the methyl benzoate yield was 53%.
[0043] Example 10 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of wheat straw biochar (concentrated at 500℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 98%, the phenol yield was 68%, and the methyl benzoate yield was 77%.
[0044] Example 11 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of wheat straw biochar (600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 100%, the phenol yield was 64%, and the methyl benzoate yield was 69%.
[0045] Example 12 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (300℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 91%, the phenol yield was 46%, and the methyl benzoate yield was 54%.
[0046] Example 13 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (400℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 97%, the phenol yield was 56%, and the methyl benzoate yield was 55%.
[0047] Example 14 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (concentrated at 500℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 96%, the phenol yield was 61%, and the methyl benzoate yield was 56%.
[0048] Example 15 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 91%, the phenol yield was 52%, and the methyl benzoate yield was 52%.
[0049] Example 16 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of corn straw biochar (300℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃ and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 86%, the phenol yield was 42%, and the methyl benzoate yield was 44%.
[0050] Example 17 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of corn straw biochar (400℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 87%, the phenol yield was 55%, and the methyl benzoate yield was 54%.
[0051] Example 18 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of corn straw biochar (concentrated at 500℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 82%, the phenol yield was 51%, and the methyl benzoate yield was 49%.
[0052] Example 19 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of corn straw biochar (600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 77%, the phenol yield was 48%, and the methyl benzoate yield was 51%.
[0053] Example 20 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rapeseed straw biochar (300℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 56%, the phenol yield was 32%, and the methyl benzoate yield was 34%.
[0054] Example 21 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rapeseed straw biochar (400℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 49%, the phenol yield was 35%, and the methyl benzoate yield was 31%.
[0055] Example 22 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rapeseed straw biochar (concentrated at 500℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 52%, the phenol yield was 43%, and the methyl benzoate yield was 48%.
[0056] Example 23 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rapeseed straw biochar (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 62%, the phenol yield was 48%, and the methyl benzoate yield was 46%.
[0057] Example 24 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 mL of isopropanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃ and reacted for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 64%, the phenol yield was 41%, the benzoic acid yield was 25%, and the isopropyl benzoate yield was 12%.
[0058] Example 25 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 mL of dimethyl sulfoxide solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was increased to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 68%, the phenol yield was 43%, and the benzoic acid yield was 45%.
[0059] Example 26 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar material (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 mL of N,N-dimethylformamide solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 45%, the phenol yield was 34%, and the benzoic acid yield was 32%.
[0060] Example 27 The application of a vanadium salt and carbon-based composite lignin depolymerization catalyst includes the following steps: 40 mg of rice straw biochar material (concentrated at 600℃), 0.0125 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 mL of distilled water were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.3 MPa. The temperature was raised to 140℃, and the reaction was carried out for 8 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 20%, the phenol yield was 13%, and the benzoic acid yield was 16%.
[0061] Comparative Example 1 The application of a lignin depolymerization catalyst includes the following steps: 40 mg of activated carbon, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 10%, the phenol yield was 5%, and the methyl benzoate yield was 2%.
[0062] Comparative Example 2 The application of a lignin depolymerization catalyst includes the following steps: 0.0110 g of vanadium acetylacetonate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 35%, the phenol yield was 8%, and the methyl benzoate yield was 1%.
[0063] Comparative Example 3 The application of a lignin depolymerization catalyst includes the following steps: 0.00837 g of acetylacetone vanadium, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, and the substrate conversion rate was determined to be 17%, and the phenol yield was 4%.
[0064] Comparative Example 4 The application of a lignin depolymerization catalyst includes the following steps: 0.00515 g of vanadium oxysulfate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which determined that the substrate conversion rate was 63%, the phenol yield was 16%, and the methyl benzoate yield was 11%.
[0065] Comparative Example 5 The application of a lignin depolymerization catalyst includes the following steps: 0.0037 g of ammonium metavanadate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, which showed that the substrate conversion rate was 11%, the phenol yield was 3%, and no other cleavage monomers were detected.
[0066] Comparative Example 6 The application of a lignin depolymerization catalyst includes the following steps: 0.0049 g of vanadium oxalate, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, and the substrate conversion rate was determined to be 3%. No other pyrolysis monomer products were detected.
[0067] Comparative Example 7 The application of a lignin depolymerization catalyst includes the following steps: 0.0077 g of triisopropanol vanadium, 42.8 mg of 2-phenoxy-1-phenylethanol substrate, and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C, and the reaction was carried out for 4 h. After the reaction was completed, the substrate conversion rate was determined to be 8% by gas chromatography.
[0068] Comparative Example 8 The application of a lignin depolymerization catalyst includes the following steps: 42.8 mg of 2-phenoxy-1-phenylethanol substrate and 5 g of methanol solvent were placed in a 50 mL high-pressure reactor with a polytetrafluoroethylene liner. The reactor was sealed, stirred, and the initial oxygen pressure was 0.5 MPa. The temperature was raised to 140 °C and the reaction was carried out for 4 h. After the reaction was completed, quantitative analysis was performed by gas chromatography, and the substrate conversion rate was determined to be 4%. No other pyrolysis monomer products were detected.
[0069] Based on the results of the above examples and comparative examples, the lignin depolymerization catalyst prepared by the synergistic effect of vanadium salt and activated carbon in this invention, under the conditions of oxidative catalysis using the lignin model compound 2-phenoxy-1-phenylethanol as a substrate, methanol as a solvent, a temperature of 140°C, and an oxygen pressure of 0.5 MPa, achieved a conversion rate of 52%–100% for 2-phenoxy-1-phenylethanol, a phenol yield of 32%–68%, and a methyl benzoate yield of 31%–77%. Among these, the catalyst combination of activated carbon and V(acac)3 in Example 7 showed the best effect, achieving a 100% conversion rate of 2-phenoxy-1-phenylethanol, a phenol yield of 68%, and a methyl benzoate yield of 77%. The results of Comparative Examples 1–7 indicate that the efficiency of vanadium salt or activated carbon alone in catalyzing the oxidative depolymerization of lignin is low; except for Comparative Example 2, which reached 35%, and Comparative Example 4, which reached 63%, the efficiency of the other comparative examples was below 20%. In the comparative examples, the yields of phenol and methyl benzoate were less than 20% and less than 15%, respectively. The results of Comparative Example 1 indicate that activated carbon alone has low catalytic oxidative depolymerization activity for lignin, with a conversion rate of 10% for 2-phenoxy-1-phenylethanol, a phenol yield of 2%, and a methyl benzoate yield of 5%.
[0070] Compared with existing technologies, the co-catalytic system of carbon-based materials and vanadium salts in this invention exhibits high catalytic efficiency and simple raw material composition. It only requires proportional addition, and the preparation and operation methods are simple. The carbon-based material is a solid, simple to prepare, and easily separated from the reaction system. It exhibits a significant synergistic catalytic effect in the catalytic depolymerization of lignin, while individual components show weak catalytic activity. When the two form a composite catalytic system, they can effectively promote substrate conversion and selective generation of target products, with catalytic efficiency far exceeding that of simple superposition of single components. This is mainly due to the unique surface structure and electronic properties of the carbon-based material, which not only provides an efficient dispersion platform for vanadium species to inhibit their aggregation and deactivation, but also regulates the electronic state and chemical environment of vanadium through interfacial interactions, stabilizing the active valence state required for the catalytic cycle. The vanadium salt, as the catalytic active center, achieves full exposure of active sites and efficient catalytic function under the synergistic effect of the carbon-based material. Therefore, the carbon-based material and vanadium salt catalytic system of this invention has the advantages of high catalytic activity and simple operation and preparation.
[0071] In summary, vanadium salts or activated carbon alone have low catalytic efficiency in the depolymerization reaction of lignin. However, when activated carbon is combined with the vanadium salt described in this invention, the efficiency of catalyzing the depolymerization reaction of lignin is significantly improved. Therefore, the vanadium salt and carbon-based lignin depolymerization catalyst provided by this invention can greatly improve production efficiency in the production of lignin depolymerization products and has high commercial value.
[0072] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.
[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include such modifications and variations.
Claims
1. A vanadium salt and carbon-based composite lignin depolymerization catalyst, characterized in that, It is composed of a mixture of vanadium salts and carbon-based compounds; The mass ratio of vanadium salt to carbon-based salt is 3.7~12.5:
40. The vanadium salt is any one of vanadium acetylacetonate, vanadium acetylacetonate oxyacetate, vanadium oxysulfate, vanadium oxyoxalate, vanadium triisopropanol oxyacetate, and ammonium metavanadate. The carbon base is biochar or activated carbon.
2. The vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 1, characterized in that, The biochar is prepared by pyrolysis of wheat straw, rice straw, corn straw or rapeseed straw at 300℃~600℃.
3. The vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 1, characterized in that, The activated carbon is any one of coal-based activated carbon, wood-based activated carbon, and fruit shell activated carbon.
4. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 1, characterized in that, Includes the following steps: Vanadium salt and carbon-based composite lignin depolymerization catalyst, solvent and lignin are added to a reaction vessel, sealed and stirred; the air in the reaction vessel is replaced with oxygen, oxygen is added to a pressure of 0.1MPa~1MPa, and the reaction is carried out at 80℃~180℃ for 2h~24h. After cooling, oxygen-containing aromatic compounds are obtained.
5. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 4, characterized in that, The mass ratio of the vanadium salt and carbon-based composite lignin depolymerization catalyst, solvent, and lignin is 43.7~52.5:42.8:4000.
6. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 4, characterized in that, The oxygen pressure is 0.5 MPa.
7. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 4, characterized in that, The reaction temperature is 100℃~180℃, and the time is 4h~24h.
8. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 7, characterized in that, The reaction temperature is 140℃.
9. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 4, characterized in that, The solvent is any one of methanol, ethanol, isopropanol, water, N,N-dimethylformamide, and dimethyl sulfoxide.
10. The application of the vanadium salt and carbon-based composite lignin depolymerization catalyst according to claim 4, characterized in that, The lignin is a β-O-4 model compound; The oxygen-containing aromatic compound is one or more of phenol, benzoic acid, methyl benzoylformate, methyl benzoate, methyl 3,4-dimethoxybenzoate, and methyl anisinate.