Lignin degradation method
The degradation of lignin by Cu catalyst supported on MgO-N under low-temperature conditions solves the problem of inefficient lignin degradation in existing technologies, achieving low-cost and high-efficiency lignin degradation, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202511210933.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2025-12-12
AI Technical Summary
Existing technologies are difficult to degrade lignin efficiently and at low cost, and conventional catalysts have problems such as strong corrosivity, high cost, high reaction temperature, and many by-products.
The preparation process is simple, and the catalyst can be recycled. The catalyst is prepared by mixing Cu with lignin and solvent in a reactor, then introducing hydrogen gas and heating to 200-300℃.
It achieves low-energy consumption and high-efficiency lignin degradation with few byproducts, making it suitable for large-scale industrial applications. The catalyst is low-cost and the reaction temperature is moderate.
Smart Images
Figure CN121107955A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical engineering technology and relates to a MgO-N supported Cu catalyst. This invention also relates to the preparation method and application of the MgO-N supported Cu catalyst. Background Technology
[0002] Lignin is a network polymer formed by phenylpropane units linked by ether and carbon-carbon bonds, exhibiting a highly heterogeneous structure that makes it difficult to degrade efficiently. Its aromatic ring structure and strong covalent bonds resist conventional chemical or biological degradation, thus requiring high-energy conditions or specific catalysts.
[0003] Currently, commonly used catalysts for lignin decomposition include homogeneous catalysts such as acids and bases, as well as heterogeneous catalysts such as metals and supported metals. Homogeneous catalysts are mostly acids and bases. Among acid catalysts, strong acids show good performance but are too corrosive. Transition metal catalysts exhibit good catalytic activity but are expensive. Therefore, researchers have explored various catalysts.
[0004] For example, Mo Jialin et al. used solid acid catalysis to degrade lignin and compared various catalysts. Evtuguin et al. investigated the possibility of using polyacid salts with high oxidation potential as catalysts for oxygen delignination of lignocellulose materials in an organic solvent-water medium. Solid acids overcome the disadvantages of liquid acids, possessing advantages such as easy separation from liquid-phase reaction systems, non-corrosiveness to equipment, simple post-treatment, and generally no environmental pollution. They can be used in a higher temperature range, expanding the application range of thermodynamically possible acid-catalyzed reactions. Guo Yuanru et al. used Keggin-structured silicotungstic acid as a catalyst to degrade activated alkali lignin in an alcohol-water system; however, as a special catalyst, the synthesis and use cost of Keggin-structured silicotungstic acid may be high. This may limit its feasibility in large-scale industrial applications. Li Guangbi et al. conducted photocatalytic degradation experiments on organic wastewater containing the lignin model compound syringol in a TiO2 suspension system using ultraviolet light (11W power, 253.7 nm) as the light source in a photocatalytic reactor and studied its reaction characteristics. However, this reaction requires photocatalytic conditions, which limits its application.
[0005] Therefore, it is particularly necessary to develop a method for lignin degradation that is low in energy consumption, high in efficiency, low in raw material cost, low in reaction temperature, high in product selectivity, and low in by-products. Summary of the Invention
[0006] The purpose of this invention is to provide a method for lignin degradation using MgO-N supported transition metal Cu as a catalyst. This method has a low reaction temperature, few byproducts, and high catalyst efficiency.
[0007] Therefore, the first technical solution provided by this invention is as follows:
[0008] A method for lignin degradation includes the following steps in sequence:
[0009] 1) The MgO-N supported Cu catalyst, lignin, and solvent were mixed in a reaction vessel;
[0010] 2) Seal the reactor, then introduce hydrogen gas, heat to 200-300℃ and react for 1.5-2.5 hours to obtain a mixture containing lignin degradation products;
[0011] The mass ratio of the MgO-N supported Cu catalyst to lignin is 0.1-0.45:0.5.
[0012] Furthermore, in the above-mentioned method for lignin degradation, the pressure in the reactor after introducing hydrogen gas is 3 MPa.
[0013] Furthermore, in the above-described method for lignin degradation, the solvent is ethanol.
[0014] Furthermore, in the above-mentioned method for lignin degradation, the MgO-N supported Cu catalyst is prepared by the following method:
[0015] 1) Dissolve MgO-N and copper nitrate in a solvent and stir to obtain a suspension;
[0016] 2) Stir the suspension at 60-70℃ for 2.5-3.5h until the solvent evaporates to dryness to obtain the MgO-N-Cu precursor;
[0017] 3) Place the MgO-N-Cu precursor obtained in step 2) in a tube furnace, introduce hydrogen to replace the oxygen in the tube, and then calcine it at 360-440℃ for 1.5-2.5h in a hydrogen atmosphere. Finally, cool it down to room temperature under nitrogen protection to obtain the MgO-N supported Cu catalyst.
[0018] Furthermore, in the above-mentioned method for lignin degradation, the MgO-N supported Cu catalyst is prepared by the following method:
[0019] 1) Dissolve MgO-N and copper nitrate in a solvent and stir to obtain a suspension;
[0020] 2) Dissolve sodium borohydride in a solvent and stir to obtain a sodium borohydride solution;
[0021] 3) Add the sodium borohydride solution prepared in step 2) dropwise to the suspension prepared in step 1), and stir for 1-2 hours;
[0022] 4) First, filter the product obtained in step 3) twice with pure water, dry it, and then filter it once with ethanol. Collect the filtered solid, dry it, and obtain the MgO-N supported Cu catalyst.
[0023] Furthermore, in the above-mentioned method for lignin degradation, the copper salt is copper nitrate.
[0024] Furthermore, in the above-mentioned method for lignin degradation, the solvent is purified water.
[0025] Furthermore, in the above-mentioned method for lignin degradation, the mass ratio of MgO-N to copper nitrate is 0.45:0.1-0.5.
[0026] Furthermore, in the above-mentioned method for lignin degradation, the MgO-N is prepared by the following method: magnesium hydroxide is placed in a muffle furnace and calcined at 500°C for 4 hours. After the solid is removed and cooled to room temperature, it is mixed and ground with melamine at a mass ratio of 2:1. Subsequently, it is placed in a tube furnace, nitrogen gas is introduced, and it is calcined at 600°C for 3 hours. The solid is then removed and cooled to room temperature to obtain white solid MgO-N.
[0027] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:
[0028] 1. The MgO-N supported Cu catalyst of the present invention has a simple preparation process, low raw material cost, high catalyst efficiency, low reaction temperature, few by-products, and high product selectivity, and is suitable for large-scale industrial degradation of lignin.
[0029] 2. The technical solution provided by this invention obtains the MgO-N supported Cu catalyst through steps such as stirring and reduction. This method is simple to operate, easy to control, and has a low catalyst preparation cost.
[0030] 3. The technical solution provided by this invention has higher efficiency and lower energy consumption, and the catalyst can be recycled, thus reducing production costs. Attached Figure Description
[0031] Figure 1 This is the gas chromatogram of the product obtained in Example 1;
[0032] Figure 2 This is the gas chromatogram of the product obtained in Example 2;
[0033] Figure 3 This is the gas chromatogram of the product obtained in Example 3;
[0034] Figure 4 This is the gas chromatogram of the product obtained in Example 4. Detailed Implementation
[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should also be understood that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention are all within the scope of protection of the present invention.
[0036] Example 1
[0037] This embodiment provides a method for lignin degradation. 15 ml of ethanol is poured into a reaction vessel. 0.3386 g of MgO-N supported Cu catalyst and 0.5 g of wood flour are added to the reaction vessel and mixed thoroughly. After sealing the reaction vessel, 3 MPa hydrogen gas is introduced, and the mixture is heated to 250°C for 2 hours to obtain a reaction solution containing lignin degradation products. The reaction solution is then filtered through a pinhole filter to separate solid particles, resulting in a reaction solution free of solid particles. After completion, 0.0090 g of dodecane is added to the reaction solution as an internal standard using a 10 μL pipette. Gas chromatography detection is then performed using the internal standard method. The GC results are as follows: Figure 1 The structural formula of the product is as follows:
[0038] , , .
[0039] The MgO-N supported Cu catalyst used in this embodiment was prepared by the following method: 30 ml of purified water was placed in a beaker, and 0.45 g of MgO-N powder and 0.377 g of copper nitrate solid were weighed and added to the beaker for mixing. The mixture was stirred with a magnetic stirrer for 5 min to obtain a suspension. The beaker was then placed in an oil bath and stirred at 80 °C for 3 h until completely dry. The blue particles in the beaker were then collected and immediately placed in a tube furnace (to prevent the solid from absorbing moisture from the air). Hydrogen gas was continuously passed through the furnace to purge the oxygen from the tube. The solid was then heated to 400 °C within 80 min in a hydrogen atmosphere (0.1 MPa), and held at 400 °C for 2 h. Finally, the temperature was lowered to room temperature under nitrogen protection. Blue solid catalyst particles with a copper mass fraction of 20% were obtained.
[0040] The MgO-N powder was prepared by the following method: magnesium hydroxide was calcined in a muffle furnace at 500°C for 4 hours. After the solid was removed and cooled to room temperature, it was mixed with melamine at a mass ratio of 2:1 and ground. Subsequently, it was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 600°C for 3 hours. After the solid was removed and cooled to room temperature, a white solid MgO-N was obtained.
[0041] Example 2
[0042] This embodiment provides a method for lignin degradation. 15 ml of ethanol is poured into a reaction vessel. 0.4401 g of MgO-N supported Cu catalyst and 0.5 g of wood flour are added to the reaction vessel and mixed thoroughly. After sealing the reaction vessel, 3 MPa hydrogen gas is introduced, and the mixture is heated to 250°C for 2 hours to obtain a reaction solution containing lignin degradation products. The reaction solution is then filtered through a pinhole filter to separate solid particles, resulting in a reaction solution free of solid particles. After completion, 0.0093 g of dodecane is added to the reaction solution as an internal standard using a 10 μL pipette. Gas chromatography detection is then performed using the internal standard method. The GC results are as follows: Figure 2 The structural formula of the product is as follows:
[0043] , , .
[0044] The MgO-N supported Cu catalyst used in this embodiment was prepared by the following method: 30 ml of purified water was placed in a beaker, and 0.45 g of MgO-N powder and 0.2837 g of copper nitrate solid were weighed and added to the beaker for mixing. The mixture was stirred with a magnetic stirrer for 5 min to obtain a suspension. The beaker was then placed in an oil bath and stirred at 80 °C for 3 h until completely dry. The blue particles in the beaker were then collected and immediately placed in a tube furnace (to prevent the solid from absorbing moisture from the air). Hydrogen gas was continuously passed through the furnace to purge the oxygen from the tube. The solid was then heated to 400 °C within 80 min in a hydrogen atmosphere (0.1 MPa), and held at 400 °C for 2 h. Finally, the temperature was lowered to room temperature under nitrogen protection. Blue solid catalyst particles with a copper mass fraction of 20% were obtained.
[0045] The MgO-N powder was prepared by the following method: magnesium hydroxide was calcined in a muffle furnace at 500°C for 4 hours. After the solid was removed and cooled to room temperature, it was mixed with melamine at a mass ratio of 2:1 and ground. Subsequently, it was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 600°C for 3 hours. After the solid was removed and cooled to room temperature, a white solid MgO-N was obtained.
[0046] Example 3
[0047] This embodiment provides a method for lignin degradation. 15 ml of ethanol is poured into a reaction vessel. 0.1560 g of MgO-N supported Cu catalyst and 0.5 g of wood flour are added to the reaction vessel and mixed thoroughly. After sealing the reaction vessel, 3 MPa hydrogen gas is introduced, and the mixture is heated to 250°C for 2 hours to obtain a reaction solution containing lignin degradation products. The reaction solution is then filtered through a pinhole filter to separate solid particles, resulting in a reaction solution free of solid particles. After completion, 0.0087 g of dodecane is added to the reaction solution as an internal standard using a 10 μL pipette. Gas chromatography detection is then performed using the internal standard method. The GC results are as follows: Figure 3 The structural formula of the product is as follows:
[0048] , , .
[0049] The MgO-N supported Cu catalyst used in this embodiment was prepared by the following method:
[0050] 1) Measure 30ml of purified water into a beaker, weigh 0.45g of MgO-N powder and 0.377g of copper nitrate solid into the beaker and mix them. Stir with a magnetic stirrer for 5 minutes to obtain a suspension. Take another beaker, add 20ml of purified water, and weigh 0.25g of sodium borohydride into the beaker and dissolve it to obtain a sodium borohydride solution.
[0051] 2) Place the beaker containing the suspension on a magnetic stirrer and add sodium borohydride solution dropwise while stirring. The entire addition process should take no less than 5 minutes, and stirring should continue for two hours. Then, filter twice with purified water, the first time using 300 ml of purified water and the second time using 250 ml. After the filter cake is dried, filter once more with 25 ml of ethanol. Collect the filtered solid, and after drying, obtain a MgO-N supported Cu catalyst with a copper element mass fraction of 20%.
[0052] The MgO-N powder was prepared by the following method: magnesium hydroxide was calcined in a muffle furnace at 500°C for 4 hours. After the solid was removed and cooled to room temperature, it was mixed with melamine at a mass ratio of 2:1 and ground. Subsequently, it was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 600°C for 3 hours. After the solid was removed and cooled to room temperature, a white solid MgO-N was obtained.
[0053] Example 4
[0054] This embodiment provides a method for lignin degradation. 15 ml of ethanol is poured into a reaction vessel. 0.4319 g of MgO-N supported Cu catalyst and 0.5 g of wood flour are added to the reaction vessel and mixed thoroughly. After sealing the reaction vessel, 3 MPa hydrogen gas is introduced, and the mixture is heated to 250°C for 2 hours to obtain a reaction solution containing lignin degradation products. The reaction solution is then filtered through a pinhole filter to separate solid particles, resulting in a reaction solution free of solid particles. After completion, 0.0094 g of dodecane is added to the reaction solution as an internal standard using a 10 μL pipette. Gas chromatography detection is then performed using the internal standard method. The GC results are as follows: Figure 4 The structural formula of the product is as follows: , , .
[0055] The MgO-N supported Cu catalyst used in this embodiment was prepared by the following method:
[0056] 1) Measure 30ml of purified water into a beaker, weigh 0.45g of MgO-N powder and 0.1885g of copper nitrate solid into the beaker and mix them. Stir with a magnetic stirrer for 5 minutes to obtain a suspension. Take another beaker, add 20ml of purified water, and weigh 0.25g of sodium borohydride and dissolve it in the beaker to obtain a sodium borohydride solution.
[0057] 2) Place the beaker containing the suspension on a magnetic stirrer and add sodium borohydride solution dropwise while stirring. The entire addition process should take no less than 5 minutes, and stirring should continue for two hours. Then, filter twice with purified water, the first time using 300 ml of purified water and the second time using 250 ml. After the filter cake is dried, filter once more with 25 ml of ethanol. Collect the filtered solid, and after drying, obtain a MgO-N supported Cu catalyst with a copper element mass fraction of 10%.
[0058] The MgO-N powder was prepared by the following method: magnesium hydroxide was calcined in a muffle furnace at 500°C for 4 hours. After the solid was removed and cooled to room temperature, it was mixed with melamine at a mass ratio of 2:1 and ground. Subsequently, it was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 600°C for 3 hours. After the solid was removed and cooled to room temperature, a white solid MgO-N was obtained.
[0059] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention will not depart from the essence and scope of the technical solution of the present invention.
Claims
1. A method for lignin degradation, characterized in that, The steps are as follows: 1) The MgO-N supported Cu catalyst, lignin, and solvent were placed in a reaction vessel and mixed; 2) Seal the reactor, then introduce hydrogen gas, heat to 200-300℃ and react for 1.5-2.5 hours to obtain lignin degradation products; The mass ratio of the MgO-N supported Cu catalyst to lignin is 0.1-0.45:0.
5.
2. The method for lignin degradation according to claim 1, characterized in that, After hydrogen gas is introduced, the pressure in the reactor is 3 MPa.
3. The method for lignin degradation according to claim 1, characterized in that, The solvent is ethanol.
4. The method for lignin degradation according to claim 1, characterized in that, The MgO-N supported Cu catalyst was prepared by the following method: 1) Dissolve MgO-N and copper nitrate in a solvent and stir to obtain a suspension; 2) Stir the suspension at 60-70℃ for 2.5-3.5h until the solvent evaporates to dryness to obtain the MgO-N-Cu precursor; 3) Place the MgO-N-Cu precursor obtained in step 2) in a tube furnace, introduce hydrogen to replace the oxygen in the tube, and then calcine it at 360-440℃ for 1.5-2.5h in a hydrogen atmosphere. Finally, cool it down to room temperature under nitrogen protection to obtain the MgO-N supported Cu catalyst.
5. The method for lignin degradation according to claim 1, characterized in that, The MgO-N supported Cu catalyst was prepared by the following method: 1) Dissolve MgO-N and copper nitrate in a solvent and stir to obtain a suspension; 2) Dissolve sodium borohydride in a solvent and stir to obtain a sodium borohydride solution; 3) Add the sodium borohydride solution prepared in step 2) dropwise to the suspension prepared in step 1), and stir for 1-2 hours; 4) First, filter the product obtained in step 3) twice with pure water, then dry it, and then filter it once with ethanol. Collect the filtered solid, and after drying, obtain the MgO-N supported Cu catalyst.
6. The method for lignin degradation according to claim 4 or 5, characterized in that, The copper salt mentioned is copper nitrate.
7. The method for lignin degradation according to claim 4 or 5, characterized in that, The solvent is purified water.
8. The method for lignin degradation according to claim 6, characterized in that, The mass ratio of MgO-N to copper nitrate is 0.45:0.1-0.
5.
9. The method for lignin degradation according to claim 4 or 5, characterized in that, The MgO-N was prepared by the following method: magnesium hydroxide was placed in a muffle furnace and calcined at 500°C for 4 hours. After the solid was removed and cooled to room temperature, it was mixed and ground with melamine at a mass ratio of 2:
1. Then, it was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 600°C for 3 hours. After the solid was removed and cooled to room temperature, white solid MgO-N was obtained.