Synthesis of temperature-controlled heterogeneous heteropolyacid catalyst and its application in lignin conversion

Abstract

This invention discloses a method for synthesizing a temperature-controlled heterogeneous heteropolyacid catalyst and its application in lignin conversion, belonging to the field of chemical degradation technology. Firstly, Mo atoms are partially replaced with Al and V atoms to synthesize the homogeneous heteropolyacid H5PMo. 11 Al 0.5 V 0.5 O 40 Then, choline chloride is added via ion exchange to synthesize a temperature-controlled heterogeneous polyacid catalyst, Ch. n H 5‑ n PMo 11 Al 0.5 V 0.5 O 40 Where n is the number of Ch atoms, and n is an integer, the heterogeneous temperature-controlled heteropolyacid catalyst can be applied to the degradation of lignin. This invention adjusts the Lewis acidity and homogeneity of the catalyst by adding Al atoms and choline chloride ionic liquid, thereby affecting the catalyst's reactivity and improving the degradation yield of lignin degradation products. The conditions are mild, the operation is simple, and it has positive significance for improving the yield of lignin degradation products.

Description

Technical Field

[0001] This invention belongs to the field of chemical degradation technology, and particularly relates to a method for synthesizing a temperature-controlled heterogeneous heteropolyacid catalyst and its application in lignin conversion. Background Technology

[0002] Faced with severe climate change and depleted fossil fuel reserves, the importance of finding sustainable and renewable energy sources has been widely recognized. In recent years, lignocellulose, as the most abundant renewable energy source on Earth (approximately 1.55 × 10⁻⁶), has emerged as a promising alternative. 11 Its annual dry matter production of tonnes makes it the preferred alternative to traditional fossil fuels.

[0003] Lignin, the most abundant renewable aromatic hydrocarbon resource on Earth, is an amorphous polymer composed of phenylpropane units linked by carbon-carbon and ether bonds. As a substitute for petrochemical materials, it has enormous potential for producing high-value chemicals such as phenolic monomers. It is a complex phenolic polymer formed from three alcohol monomers (p-coumarol, coniferyl alcohol, and sinapyl alcohol). Due to its three-dimensional network structure, suitable carbon-hydrogen ratio, and the availability of numerous active phenolic hydroxyl groups, rigid benzene rings, and carbonyl groups, lignin has been considered a material with adsorption, biomass combustion, anti-aging, and antioxidant properties. As the only biomass resource in nature containing a benzene ring, lignin has great potential for conversion into aromatic or cycloalkanes for use in liquid fuels.

[0004] However, the stubborn and complex structure of lignin makes the utilization of lignocellulose extremely difficult. In recent years, a "lignin-first" strategy has been widely recognized as the first and crucial step in the efficient conversion of biomass resources. The key to this technology is the effective and selective cleavage of the CO bonds on aryl ethers, while avoiding the formation of C-C bonds after CO bond cleavage, which would lead to lignin re-condensation, thus obtaining highly selective lignin monomers for utilization. In this process, finding the most suitable catalyst and depolymerization process has become a hot topic in lignin depolymerization. Summary of the Invention

[0005] To address the problems of low yield and oxidative degradation of lignin using single heteropolyacid catalysts, this invention proposes a method for synthesizing a temperature-controlled heterogeneous heteropolyacid catalyst and its application in lignin conversion. The temperature-controlled heterogeneous heteropolyacid catalyst prepared by this invention can efficiently oxidize and degrade lignin, while simultaneously degrading aromatic compounds from lignin, with a significant improvement in both product yield and efficiency.

[0006] One objective of this invention is to provide a method for synthesizing a temperature-controlled heterogeneous heteropolyacid catalyst, which first involves partially replacing V with Al to synthesize the homogeneous heteropolyacid H5PMo. 11 Al0.5 V 0.5 O 40 Then, choline chloride is added via ion exchange to synthesize a temperature-controlled heterogeneous polyacid catalyst, Ch. n H 5-n PMo 11 Al 0.5 V 0.5 O 40 n is the number of Ch, and n can be an integer.

[0007] This invention adjusts the Lewis acidity and homogeneity of the catalyst by adding Al atoms and choline chloride ionic liquid, thereby affecting the catalyst's reactivity and improving the degradation yield of lignin degradation products. The conditions are mild and the operation method is simple, which is of positive significance for improving the yield of lignin degradation products.

[0008] Furthermore, the synthesis method of the temperature-controlled heterogeneous heteropolyacid catalyst includes the following steps:

[0009] H3PO4, AlCl3·H2O, V2O5, and MoO3 were dissolved in water and stirred thoroughly under heating. After cooling to room temperature, insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 ; the H5PMo 11 Al 0.5 V 0.5 O 40 Dissolved in water, yielding H5PMo 11 Al 0.5 V 0.5 O 40 Solution; add choline chloride solution dropwise to the H5PMo 11 Al 0.5 V 0.5 O 40 In the solution, the mixture was stirred, filtered under reduced pressure, and washed with water until no white precipitate was detected in the AgNO3 solution. Vacuum drying yielded the temperature-controlled heterogeneous heteropolyacid catalyst Ch. n H 5-n PMo 11 Al 0.5 V 0.5 O 40 n is the number of Ch, and n can be an integer, preferably n = 1, 2, 3, 4 or 5.

[0010] Furthermore, the molar ratio of H3PO4, AlCl3·H2O, V2O5 and MoO3 is 1∶0.25∶0.12∶11.

[0011] Furthermore, the heating temperature is 80-90°C, preferably 80°C, and the heating time is 6 hours.

[0012] Furthermore, the temperature of the water bath is 80-90°C, preferably 85°C, and the time is 24 hours.

[0013] Furthermore, after adding choline chloride solution, the stirring temperature was 18–22°C, and the stirring time was 12 hours.

[0014] Furthermore, the preparation method of the choline chloride solution is as follows: Weigh 0.28g (2mmol) of choline chloride, dissolve it in 10mL of water, heat and stir until completely dissolved to obtain the choline chloride solution.

[0015] Furthermore, the H5PMo 11 Al 0.5 V 0.5 O 40 H5PMo in solution 11 Al 0.5 V 0.5 O 40 The molar ratio of choline chloride to the choline chloride solution is 1:1.

[0016] Furthermore, when Ch n H 5-n PMo 11 Al 0.5 V 0.5 O 40 When n=1, the temperature-controlled heterogeneous heteropolyacid catalyst ChH4PMo 11 Al 0.5 V 0.5 O 40 The synthesis method and specific preparation method are as follows:

[0017] 0.58 g (0.01 mol) of 85% H3PO4, 0.6 g (0.0025 mol) of AlCl3·H2O, 0.22 g (0.0012 mol) of V2O5, and 14.4 g (0.11 mol) of MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 Weigh out H5PMo 11 Al 0.5 V 0.5 O 403.54 g (2 mmol) was dissolved in 10 mL of water to obtain H5PMo 11 Al 0.5 V 0.5 O 40 Solution; Weigh 0.28 g (2 mmol) of choline chloride (Ch) and dissolve it in 10 mL of water. Heat and stir until completely dissolved to obtain a choline chloride solution; Slowly add the choline chloride solution dropwise to the H5PMo solution. 11 Al 0.5 V 0.5 O 40 The solution was stirred at room temperature for 12 hours, filtered under reduced pressure, and repeatedly washed with deionized water until no white precipitate was detected in AgNO3 solution. The solution was then dried under vacuum to obtain the temperature-controlled heterogeneous heteropolyacid catalyst ChH4PMo. 11 Al 0.5 V 0.5 O 40 .

[0018] The second objective of this invention is to provide a temperature-controlled heterogeneous heteropolyacid catalyst synthesized according to the above-described synthesis method.

[0019] The third objective of this invention is to provide an application of the temperature-controlled heterogeneous heteropolyacid catalyst described above in lignin conversion.

[0020] Furthermore, the lignin is the lignin obtained from biomass after removing cellulose and hemicellulose.

[0021] The fourth objective of this invention is to provide a method for degrading lignin using the temperature-controlled heterogeneous heteropolyacid catalyst, comprising the following steps:

[0022] Lignin and a temperature-controlled heterogeneous heteropolyacid catalyst were added to the reaction solvent and reacted. After the reaction was completed, the mixture was cooled, and the reaction solution was removed by filtration to remove the residue. The methanol was evaporated by a first rotary evaporator. The product after rotary evaporation was then extracted with dichloromethane and distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water, and the dichloromethane was evaporated by a second rotary evaporator to obtain the lignin oil product.

[0023] Furthermore, in the method for degrading lignin using a temperature-controlled heterogeneous heteropolyacid catalyst, the mass ratio of lignin to the temperature-controlled heterogeneous heteropolyacid catalyst is 2:1.

[0024] Furthermore, in the method for degrading lignin using a temperature-controlled heterogeneous heteropolyacid catalyst, the reaction temperature between lignin and the temperature-controlled heterogeneous heteropolyacid catalyst is 140–160 °C, and the reaction time is 120–240 min. The reaction between lignin and the temperature-controlled heterogeneous heteropolyacid catalyst is carried out under stirring conditions at a speed of 400–600 rpm.

[0025] Furthermore, in the method for degrading lignin using a temperature-controlled heterogeneous heteropolyacid catalyst, the reaction solvent is methanol or methanol / water, where methanol / water refers to a mixed solvent of methanol and water. When the reaction solvent is a mixed solvent of methanol and water, the volume ratio of methanol to water is 8:2 or 6:4.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] (1) The catalyst used in this invention for lignin degradation is a temperature-controlled heterogeneous heteropolyacid catalyst. By adding Al atoms and choline chloride ionic liquid, the Lewis acidity of the catalyst is adjusted and its homogeneity is changed, thereby affecting the reaction activity of the catalyst and improving the degradation yield of lignin degradation products.

[0028] (2) This invention provides a new catalyst for improving the degradation of lignin by aromatic monomers. The lignin degradation process is carried out in a high-pressure reactor under mild conditions and simple operation. Therefore, this invention has a positive significance for improving the yield of lignin degradation products, provides a new development technology for lignin degradation, and has great significance for sustainable development. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 Here is a GC-MS image of lignin degradation under phosphotungstic acid catalysis.

[0031] Figure 2 Ch4HPMo 11 Al 0.5 V 0.5 O 40 GC-MS image of lignin degradation under catalytic conditions. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] The lignocellulose used in the embodiments of the present invention is one of the following: defatted ball-milled fir, larch wood powder, melon seed shells, rice straw, cypress seed shells, hazelnut shells, and pine nut shells.

[0038] In this embodiment of the invention, room temperature refers to 25±2℃.

[0039] In some embodiments of the present invention, the defatted and ball-milled fir is summer fir wood powder, which is prepared by: crushing the dried fir wood with a pulverizer, sieving it through a sieve of 40-60 mesh, defatting it in an oil bath using a Soxhlet extractor at a temperature of 90°C for 6 hours, and then ball-milling it in a planetary ball mill for 4 hours.

[0040] In some embodiments of the present invention, the defatted ball-milled larch wood powder, melon seed shells, rice straw, cypress seed shells, hazelnut shells, and pine nut shells are all prepared by the same defatted ball-milling process as fir wood powder.

[0041] Example 1

[0042] Preparation of methanol-pretreated lignin: Pine nut shells were extracted and defatted using a Soxhlet extractor, then ball-milled in a planetary ball mill. 0.2g of the ball-milled pine nut shells and 0.1g of phosphotungstic acid (H3PW) were then added. 12 O 40 The product was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. 10 mL of methanol / water solvent (volume ratio 8:2) was mixed and reacted in a high-pressure reactor at 160℃, 600 rpm, and 1 MPa O2 was introduced for 4 hours. After the reaction, the mixture was cooled for 1 hour. The reaction solution was then removed and filtered through a funnel to remove residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50℃. The evaporated product was then repeatedly extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water, and the dichloromethane was evaporated again using a rotary evaporator at 40℃ to obtain the lignin oil product.

[0043] The obtained lignin oil product was added to 4 mL of ethyl acetate and stored in a centrifuge tube. The reaction solution was then filtered using a filter syringe. An internal standard was then added using a pneumatic air gun. The internal standard was prepared as follows: 0.12 g of 3,5-dimethylphenol was diluted to 10 mL of chromatographically pure ethyl acetate.

[0044] The solution prepared in the previous step was subjected to gas chromatography-mass spectrometry (GC-MS). The instrument used was an Agilent 6890N / 5973i. The required detection conditions were as follows: HP-5MS capillary column; temperature program: initial 70℃, maintained for 2 min, then increased to 180℃ at 7℃ / min and maintained for 8 min; detector: FID (200℃); internal standard: 3,5-dimethoxyphenol; carrier gas: helium; split ratio: 5.01:1; injection port and injection volume: 180℃, 1 μL.

[0045] Figure 1 The image shows the GC-MS chromatogram of lignin degradation under phosphotungstic acid catalysis. The monomer products and yields during lignin degradation are shown in Table 1, with a total yield of 2.41%.

[0046] Table 1. Monomer products and yields during lignin degradation.

[0047]

[0048] Example 2

[0049] catalyst H5PMo 11 Al 0.5 V 0.5 O 40Preparation: 0.58 g (0.01 mol) 85% H3PO4, 0.6 g (0.0025 mol) AlCl3·H2O, 0.22 g (0.0012 mol) V2O5, and 14.4 g (0.11 mol) MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 .

[0050] Preparation of methanol-pretreated lignin: Fir wood powder was extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2g of the ball-milled fir wood powder and 0.1g of the prepared H5PMo were then added... 11 Al 0.5 V 0.5 O 40 Mix 10 mL of methanol solvent and react in a high-pressure reactor at 150 °C, 500 rpm, and 1 MPa O2 for 2 h. After the reaction is complete, cool for 1 h, remove the reaction solution and filter it in a funnel to remove the residue. Wash the residual solution in the reactor with methanol solution. Use a rotary evaporator to evaporate the methanol at 50 °C. Then, extract the evaporated product three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Add anhydrous magnesium sulfate to remove excess water, and use a rotary evaporator again to evaporate the dichloromethane at 40 °C to obtain the lignin oil product.

[0051] The subsequent processing conditions are the same as in Example 1.

[0052] The monomer products and yields during lignin degradation are shown in Table 2, with a total yield of 4.68%.

[0053] Table 2. Monomer products and yields during lignin degradation.

[0054]

[0055] Example 3

[0056] Preparation of temperature-controlled heterogeneous heteropolyacid catalyst ChH4PMo 11 Al 0.5 V 0.5 O 400.58 g (0.01 mol) of 85% H3PO4, 0.6 g (0.0025 mol) of AlCl3·H2O, 0.22 g (0.0012 mol) of V2O5, and 14.4 g (0.11 mol) of MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 Weigh out H5PMo 11 Al 0.5 V 0.5 O 40 3.54 g (2 mmol) was dissolved in 10 mL of water to obtain H5PMo 11 Al 0.5 V 0.5 O 40 Solution; Weigh 0.28 g (2 mmol) of choline chloride and dissolve it in 10 mL of water. Heat and stir until completely dissolved to obtain a choline chloride solution; Slowly add the above choline chloride solution dropwise to the above H5PMo solution. 11 Al 0.5 V 0.5 O 40 The solution was stirred at room temperature for 12 hours, filtered under reduced pressure, and repeatedly washed with deionized water until no white precipitate was detected in AgNO3 solution. The solution was then dried under vacuum to obtain the temperature-controlled heterogeneous heteropolyacid catalyst ChH4PMo. 11 Al 0.5 V 0.5 O 40 .

[0057] Preparation of methanol-pretreated lignin: Larch wood powder was extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2 g of the ball-milled larch wood powder and 0.1 g of the prepared ChH4PMo were then added... 11 Al 0.5 V 0.5 O 4010 mL of methanol / water solvent (volume ratio 8:2) was mixed and reacted in a high-pressure reactor at 140℃, 400 rpm, and 1 MPa O2 was introduced for 3 h. After the reaction was completed, the mixture was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove the residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50℃. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40℃ to obtain the lignin oil product.

[0058] The subsequent processing conditions are the same as in Example 1.

[0059] The monomer products and yields during lignin degradation are shown in Table 3, with an overall yield of 6.21%.

[0060] Table 3. Monomer products and yields during lignin degradation.

[0061]

[0062] As shown in Tables 1-3, the temperature-controlled heterogeneous heteropolyacid catalyst prepared in this invention exhibits an advantage in monomer product yield for lignin degradation compared to lignin degradation without catalyst addition. Therefore, the method of this invention can promote lignin degradation and achieve higher degradation yields, which is beneficial for the development of lignin degradation-related technologies.

[0063] Example 4

[0064] Preparation of temperature-controlled heterogeneous heteropolyacid catalyst Ch2H3PMo 11 Al 0.5 V 0.5 O 40 0.58 g (0.01 mol) of 85% H3PO4, 0.6 g (0.0025 mol) of AlCl3·H2O, 0.22 g (0.0012 mol) of V2O5, and 14.4 g (0.11 mol) of MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 Weigh out H5PMo 11 Al 0.5 V 0.5 O 40Dissolve 3.54 g (2 mmol) in 10 mL of water. Simultaneously, weigh out 0.56 g (4 mmol) of choline chloride and dissolve it in 10 mL of water. Heat and stir until completely dissolved. Slowly add the choline chloride solution dropwise to H5PMo. 11 Al 0.5 V 0.5 O 40 The solution was stirred at room temperature for 12 hours. It was then filtered under reduced pressure and repeatedly washed with deionized water until no white precipitate formed as detected by AgNO3 solution. The solution was then dried under vacuum to obtain Ch₂H₃PMo. 11 Al 0.5 V 0.5 O 40 .

[0065] Preparation of methanol-pretreated lignin: Rice straw was extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2g of the ball-milled rice straw and 0.1g of Ch2H3PMo prepared as described above were then added. 11 Al 0.5 V 0.5 O 40 10 mL of methanol / water solvent (volume ratio 8:2) was mixed and reacted in a high-pressure reactor at 160℃, 400 rpm, and 1 MPa O2 was introduced for 4 h. After the reaction was completed, the mixture was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove the residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50℃. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40℃ to obtain the lignin oil product.

[0066] The subsequent processing conditions are the same as in Application Example 1.

[0067] The monomer products and yields during lignin degradation are shown in Table 4, with an overall yield of 5.44%.

[0068] Table 4. Monomer products and yields during lignin degradation

[0069]

[0070] Example 5

[0071] Preparation of temperature-controlled heterogeneous heteropolyacid catalyst Ch3H2PMo 11 Al 0.5 V 0.5 O 400.58 g (0.01 mol) of 85% H3PO4, 0.6 g (0.0025 mol) of AlCl3·H2O, 0.22 g (0.0012 mol) of V2O5, and 14.4 g (0.11 mol) of MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 Weigh out H5PMo 11 Al 0.5 V 0.5 O 40 Dissolve 3.54 g (2 mmol) in 10 mL of water. Simultaneously, weigh out 0.84 g (6 mmol) of choline chloride and dissolve it in 10 mL of water. Heat and stir until completely dissolved. Slowly add the choline chloride solution dropwise to H5PMo. 11 Al 0.5 V 0.5 O 40 The solution was stirred at room temperature for 12 hours. It was then filtered under reduced pressure and repeatedly washed with deionized water until no white precipitate formed as detected by AgNO3 solution. The solution was then dried under vacuum to obtain Ch3H2PMo. 11 Al 0.5 V 0.5 O 40 .

[0072] Preparation of methanol-pretreated lignin: Sunflower seed shells were extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2g of the ball-milled sunflower seed shells and 0.1g of the catalyst Ch3H2PMo prepared above were then added. 11 Al 0.5 V 0.5 O 40 10 mL of methanol / water (volume ratio 8:2) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was then removed and filtered through a funnel to remove residue. The residue in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water, and the dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0073] The subsequent processing conditions are the same as in Application Example 1.

[0074] The monomer products and yields during lignin degradation are shown in Table 5, with an overall yield of 5.26%.

[0075] Table 5. Monomer products and yields during lignin degradation.

[0076]

[0077]

[0078] Example 6

[0079] Preparation of temperature-controlled heterogeneous heteropolyacid catalyst Ch4HPMo 11 Al 0.5 V 0.5 O 40 0.58 g (0.01 mol) of 85% H3PO4, 0.6 g (0.0025 mol) of AlCl3·H2O, 0.22 g (0.0012 mol) of V2O5, and 14.4 g (0.11 mol) of MoO3 were dissolved in 150 mL of deionized water. The solution was stirred at 80 °C for 6 hours. After cooling to room temperature, the insoluble molybdate and vanadate were removed by filtration. The resulting polyacid solution was evaporated in a water bath at 85 °C for 24 hours to obtain orange-yellow crystals H5PMo. 11 Al 0.5 V 0.5 O 40 Weigh out H5PMo 11 Al 0.5 V 0.5 O 40 Dissolve 3.54 g (2 mmol) in 10 mL of water. Simultaneously, weigh 1.12 g (8 mmol) of choline chloride and dissolve it in 10 mL of water. Heat and stir until completely dissolved. Slowly add the choline chloride solution dropwise to H5PMo. 11 Al 0.5 V 0.5 O 40 The solution was stirred at room temperature for 12 hours. It was then filtered under reduced pressure and repeatedly washed with deionized water until no white precipitate formed as detected by AgNO3 solution. The solution was then dried under vacuum to obtain Ch4HPMo. 11 Al 0.5 V 0.5 O 40 .

[0080] Preparation of methanol-pretreated lignin: Hazelnut shells were extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2g of the ball-milled hazelnut shells and 0.1g of Ch4HPMo prepared as described above were then added. 11 Al 0.5 V 0.5 O40 The reaction solvent (6 mL: 4 mL methanol / water) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C. The reaction was carried out for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove residue. The residue in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0081] The subsequent processing conditions are the same as in Application Example 1.

[0082] The monomer products and yields during lignin degradation are shown in Table 6, with an overall yield of 2.91%.

[0083] Table 6. Monomer products and yields during lignin degradation.

[0084]

[0085] Example 7

[0086] Preparation of methanol-pretreated lignin: After degreasing cypress seed husks using a Soxhlet extractor, the husks were further degreased and ball-milled in a planetary ball mill. 0.2 g of the ball-milled cypress seed husks and 0.1 g of the catalyst ChH4PMo synthesized according to the method in Example 3 were then added. 11 Al 0.25 V 0.75 O 40 The reaction solvent (6 mL: 4 mL methanol / water) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C. The reaction was carried out for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove residue. The residue in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0087] The subsequent processing conditions are the same as in Application Example 1.

[0088] The monomer products and yields during lignin degradation are shown in Table 7, with an overall yield of 4.18%.

[0089] Table 7. Monomer products and yields during lignin degradation.

[0090]

[0091] Example 8

[0092] Preparation of methanol-pretreated lignin: Larch wood powder was extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2 g of the ball-milled larch wood powder and 0.1 g of the catalyst Ch2H3PMo synthesized according to the method in Example 4 were then added. 11 Al 0.5 V 0.5 O 40 The reaction solvent (8 mL: 2 mL methanol / water) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C. The reaction was carried out for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0093] The subsequent processing conditions are the same as in Application Example 1.

[0094] The monomer products and yields during lignin degradation are shown in Table 8, with an overall yield of 5.04%.

[0095] Table 8. Monomer products and yields during lignin degradation

[0096]

[0097] Example 9

[0098] Preparation of methanol-pretreated lignin: Pine nut shells were extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2 g of the ball-milled pine nut shells and 0.1 g of the catalyst Ch3H2PMo synthesized according to the method in Example 5 were then added. 11 Al 0.5 V 0.5 O 40The reaction solvent (8 mL: 2 mL methanol / water) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C. The reaction was carried out for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0099] The subsequent processing conditions are the same as in Application Example 1.

[0100] The monomer products and yields during lignin degradation are shown in Table 9, with a total yield of 4.07%.

[0101] Table 9. Monomer products and yields during lignin degradation.

[0102]

[0103] Example 10

[0104] Preparation of methanol-pretreated lignin: Larch fir wood powder was extracted and defatted using a Soxhlet extractor, then defatted and ball-milled in a planetary ball mill. 0.2 g of the ball-milled larch fir wood powder and 0.1 g of the catalyst Ch4HPMo synthesized according to Example 6 were then added. 11 Al 0.5 V 0.5 O 40 The reaction solvent (8 mL: 2 mL methanol / water) was added to a high-pressure reactor. After sealing and purging with oxygen to remove air from the reactor, oxygen was introduced to a pressure of 1 MPa. The reaction speed was set at 600 rpm, and the reactor temperature was set at 160 °C. The reaction was carried out for 240 min. After the reaction was completed, the reactor was cooled for 1 h. The reaction solution was removed and filtered through a funnel to remove residue. The residual solution in the reactor was washed with methanol solution. The methanol was evaporated using a rotary evaporator at 50 °C. The evaporated product was then extracted three times with 20 mL of dichloromethane and 20 mL of distilled water to obtain the organic phase. Anhydrous magnesium sulfate was added to remove excess water. The dichloromethane was evaporated again using a rotary evaporator at 40 °C to obtain the lignin oil product.

[0105] Ch4HPMo 11 Al 0.5 V 0.5 O40 GC-MS image of lignin degradation under catalytic conditions is shown below Figure 2 .

[0106] The subsequent processing conditions are the same as in Application Example 1.

[0107] The monomer products and yields during lignin degradation are shown in Table 10, with a total yield of 2.74%.

[0108] Table 10. Monomer products and yields during lignin degradation.

[0109]

[0110] As can be seen from the above examples, more Ch is not necessarily better; the best results are achieved when Ch = 1 or 2.

[0111] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for synthesizing a temperature-controlled heterogeneous heteropolyacid catalyst, characterized in that, First, the homogeneous heteropolyacid H5PMo was synthesized by partially replacing Mo atoms with Al and V atoms. 11 Al 0.5 V 0.5 O 40 Then, choline chloride is added via ion exchange to synthesize a temperature-controlled heterogeneous polyacid catalyst, Ch. n H 5-n PMo 11 Al 0.5 V 0.5 O 40 n is the number of Ch, and n can be an integer.

2. The method for synthesizing the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 1, characterized in that, Includes the following steps: H3PO4, AlCl3·H2O, V2O5, and MoO3 were dissolved in water, stirred thoroughly under heating, cooled to room temperature, and filtered. The resulting polyacid solution was then evaporated in a water bath to obtain H5PMo. 11 Al 0.5 V 0.5 O 40 ; the H5PMo 11 Al 0.5 V 0.5 O 40 Dissolved in water, yielding H5PMo 11 Al 0.5 V 0.5 O 40 Solution; add choline chloride solution dropwise to the H5PMo 11 Al 0.5 V 0.5 O 40 In the solution, the mixture was stirred, filtered under reduced pressure, and washed with water until no white precipitate was detected in the AgNO3 solution. Vacuum drying yielded the temperature-controlled heterogeneous heteropolyacid catalyst Ch. n H 5-n PMo 11 Al 0.5 V 0.5 O 40 n is the number of Ch, and n can be an integer.

3. The method for synthesizing the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 2, characterized in that, The molar ratio of H3PO4, AlCl3·H2O, V2O5 and MoO3 is 1:0.25:0.12:

11.

4. The method for synthesizing the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 2, characterized in that, The heating temperature is 80-90℃, and the heating time is 6 hours.

5. The method for synthesizing the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 2, characterized in that, The water bath temperature is 80-90℃, and the time is 24 hours.

6. The method for synthesizing the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 2, characterized in that, After adding choline chloride solution, the stirring temperature was 18–22°C for 12 hours.

7. A temperature-controlled heterogeneous heteropolyacid catalyst, characterized in that, Synthesized according to any one of claims 1 to 6.

8. The application of the temperature-controlled heterogeneous heteropolyacid catalyst according to claim 7 in lignin conversion.

9. A method for degrading lignin using a temperature-controlled heterogeneous heteropolyacid catalyst as described in claim 7, characterized in that, Includes the following steps: Lignin and a temperature-controlled heterogeneous heteropolyacid catalyst were added to the reaction solvent and reacted. After the reaction was completed, the mixture was cooled, the reaction solution was removed and filtered, and the product was subjected to a first rotary evaporation. The product after the first rotary evaporation was then extracted with dichloromethane and distilled water to obtain the organic phase. Anhydrous magnesium sulfate was then added, and the product was subjected to a second rotary evaporation to obtain an oily lignin product.

10. The method for degrading lignin using a temperature-controlled heterogeneous heteropolyacid catalyst according to claim 9, characterized in that, The mass ratio of lignin to temperature-controlled heterogeneous heteropolyacid catalyst is 2:1.

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