Biomass liquid fuel and preparation method thereof

Abstract

The invention relates to the technical field of biomass liquid fuels, in particular to a biomass liquid fuel and a preparation method thereof, and the biomass liquid fuel comprises the following components by weight: 40-60 parts of biomass-based methanol; 10 to 20 parts of biomass-based ethanol; 5 to 15 parts of biomass-based n-butyl alcohol; 5 to 10 parts of dimethyl ether; 10 to 20 parts of biodiesel; 1-5 parts of a lignin derivative; 0.1 to 0.5 part of an antioxidant; 0.1 to 0.5 part of a stabilizing agent; 0.5-2 parts of a purification dispersant; 1-3 parts of bio-based glycerol n-butyl ether; according to the invention, a plurality of alcohols (methanol, ethanol and n-butyl alcohol) are synergistically used, so that a series with the carbon chain length gradually increasing from C1 to C4 is formed. According to the design, the volatility and the energy density of the fuel are balanced, the oxygen content of the fuel is increased through hydroxyl (-OH) in alcohol molecules, and more complete combustion is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass liquid fuel, and in particular to a biomass liquid fuel and a preparation method thereof. Background Art

[0002] As the global energy crisis and environmental problems become increasingly severe, the development of clean, renewable alternative fuels has become an important research direction in the current energy field. As a renewable resource, biomass has a wide range of sources and huge potential. However, how to efficiently convert biomass into high-quality liquid fuels still faces many challenges.

[0003] At present, the research on biomass liquid fuels mainly focuses on single-component fuels such as bioethanol and biodiesel. Although these fuels have achieved the replacement of fossil fuels to a certain extent, there are still many problems. For example, bioethanol has a low energy density and is easy to absorb water, which affects the stability of the fuel; biodiesel is easy to crystallize under low temperature conditions, which affects its scope of use. In addition, the production of these fuels often only utilizes some components in biomass, such as starch, sugars or oils, while ignoring other valuable components, such as cellulose and lignin, resulting in low resource utilization. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention proposes a multi-component synergistic biomass liquid fuel and a preparation method thereof.

[0005] The object of the present invention is to provide a biomass liquid fuel, which comprises the following components by weight:

[0006] 40-60 parts of biomass-based methanol;

[0007] Biomass-based ethanol 10-20 parts;

[0008] 5-15 parts of biomass-based n-butanol;

[0009] 5-10 parts of dimethyl ether;

[0010] Biodiesel 10-20 parts;

[0011] 1-5 parts of lignin derivative;

[0012] Antioxidant 0.1-0.5 parts;

[0013] Stabilizer 0.1-0.5 parts;

[0014] 0.5-2 parts of detergent dispersant;

[0015] 1-3 parts of bio-based glycerol n-butyl ether;

[0016] 0.5-2 parts of dimethyl 2,5-furandicarboxylate.

[0017] Preferably, the antioxidant comprises tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:1.

[0018] Preferably, the stabilizer comprises N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1: 1. TMQ is poly (1,2-dihydro-2,2,4-trimethylquinoline).

[0019] Preferably, the detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:1.

[0020] A method for preparing biomass liquid fuel comprises the following steps:

[0021] (1) Preparation of biomass-based methanol;

[0022] (2) preparing biomass-based ethanol;

[0023] (3) preparing biomass-based n-butanol;

[0024] (4) Preparation of dimethyl ether;

[0025] (5) Preparation of biodiesel;

[0026] (6) preparing lignin derivatives;

[0027] (7) preparing bio-based glycerol n-butyl ether;

[0028] (8) preparing dimethyl 2,5-furandicarboxylate;

[0029] (9) The components are mixed in the proportions described in claim 1.

[0030] Preferably, step (1) comprises: first, mixing the lignocellulosic biomass raw material with water in a mass ratio of 1:5-1:10; second, performing hydrothermal pretreatment at 200-300°C and 5-10MPa for 30-60 minutes; then, supercritical water gasification of the pretreated liquid phase at 250-350°C and 15-25MPa for 5-15 minutes to obtain synthesis gas; third, synthesizing methanol from the synthesis gas at 220-280°C and 5-10MPa over a Cu / ZnO / Al2O3 catalyst for 2-4 hours; finally, condensing and distilling to obtain biomass-based methanol with a purity of more than 99.5%;

[0031] Step (2) comprises: first, mixing starchy or sugary biomass raw materials with water; second, adding α-amylase and liquefying at 90-95° C. for 2-3 hours; then, cooling to 60-65° C., adding glucose amylase for saccharification for 24-48 hours; third, cooling the saccharified liquid to 30-35° C., adding yeast for fermentation for 48-72 hours; finally, distilling and rectifying the fermented liquid to obtain biomass-based ethanol with a purity of more than 95%;

[0032] Step (3) comprises: first, pre-treating the cellulose biomass raw material with alkali; second, adding cellulase for enzymolysis and reacting at 50-55° C. for 48-72 hours; then, cooling the enzymolysis solution to 35-40° C., adding Clostridium butyricum for ABE fermentation for 72-96 hours; finally, extracting and distilling the fermentation solution to obtain biomass-based n-butanol with a purity of more than 98%.

[0033] Preferably, step (4) comprises: first, introducing part of the biomass-based methanol obtained in step (1) into a fixed bed reactor; second, carrying out a dehydration reaction for 1-3 hours over a γ-Al2O3 catalyst at 250-400°C and 0.5-2MPa; and finally, condensing and rectifying the product to obtain dimethyl ether with a purity of more than 99%;

[0034] Step (5) comprises: first, mixing vegetable oil or animal oil with methanol in a molar ratio of 1:6; second, adding 1-2% (mass ratio) of KOH catalyst; then, stirring and reacting at 60-65° C. for 1-2 hours; third, standing and stratifying to separate the lower layer of glycerol; finally, washing the upper layer of crude biodiesel with water and drying to obtain biodiesel with a purity of more than 98%;

[0035] Step (6) comprises: first, drying and crushing the solid phase separated in step (1), wherein the solid phase is mainly lignin; second, adding ethanol for solvation and liquefaction for 2-4 hours at 200-250°C and 2-5MPa; then, cooling and filtering; finally, removing most of the ethanol from the filtrate by vacuum distillation to obtain a lignin derivative.

[0036] Preferably, step (7) comprises: first, mixing the glycerol separated in step (5) with n-butanol in a molar ratio of 1:4; second, adding 5% (mass ratio) of Amberlyst-15 ion exchange resin as a catalyst; then, reacting at 120-140° C. and 0.5-1 MPa for 4-6 hours; finally, cooling and filtering to remove the catalyst, and obtaining bio-based glycerol n-butyl ether with a purity of more than 95% by reduced pressure distillation;.

[0037] Preferably, the step (8) further comprises:

[0038] First, add the components into the mixing tank in sequence according to the stated proportions;

[0039] Secondly, stirring and mixing at 40-60°C for 2-4 hours;

[0040] Then, filter after standing for 24 hours;

[0041] Finally, the mixture was treated in an ultrasonic processor for 30 minutes, with an ultrasonic frequency of 20-40 kHz and a power density of 300-500 W / L.

[0042] Preferably, each reaction in step (1) to step (7) is carried out under an inert gas atmosphere, and the inert gas is selected from nitrogen, argon or a mixture thereof.

[0043] The innovative features and technical effects of the present invention are mainly reflected in the following aspects:

[0044] The fuel not only contains traditional bioethanol and biodiesel, but also innovatively introduces biomass-based methanol, biomass-based n-butanol, lignin derivatives and other components. This unique formula design makes full use of the various components of biomass and realizes the full-component and high-value utilization of biomass resources.

[0045] From the perspective of molecular structure and chemical mechanism, the innovation of the present invention is mainly reflected in the following aspects:

[0046] First, the coordinated use of multiple alcohols (methanol, ethanol, and n-butanol) forms a series with carbon chain lengths gradually increasing from C1 to C4. This design not only balances the volatility and energy density of the fuel, but also increases the oxygen content of the fuel through the hydroxyl group (-OH) in the alcohol molecules, promoting more complete combustion.

[0047] Secondly, the introduction of lignin derivatives is a highlight of the present invention. Lignin is a complex aromatic polymer, and its derivatives contain a large number of phenolic structures. These phenolic compounds not only have high calorific value, but also have natural antioxidant properties, which can form a synergistic effect with the added antioxidants and significantly improve the oxidation stability of the fuel.

[0048] Thirdly, the addition of bio-based glycerol n-butyl ether is an innovative way to solve the low-temperature performance of biofuels. This compound combines the polar part of glycerol with the non-polar part of n-butyl, which can effectively reduce the freezing point and cold filter point of the fuel, while also increasing the oxygen content of the fuel.

[0049] Finally, the introduction of dimethyl 2,5-furandicarboxylate (FDME) reflects the comprehensive consideration of fuel performance in the present invention. As a new type of bio-based additive, FDME can not only improve the cetane number of the fuel, but also play a role in reducing the temperature during the combustion process, which helps to reduce NOx emissions.

[0050] In terms of preparation method, the present invention adopts innovative processes such as ultrasonic treatment, which may break up macromolecules through cavitation effect and promote uniform mixing of various components, thereby achieving precise control of fuel components at the molecular level.

[0051] In summary, the present invention successfully integrates biomass components of different sources and properties into a synergistic whole through ingenious molecular design and innovative preparation process. This multi-component synergistic design not only overcomes the limitations of single-component biofuels, but also produces a series of unexpected technical effects, such as ultra-high octane number, excellent low-temperature performance, significantly improved oxidation stability and overall reduced emission levels.

[0052] The significance of the present invention is not only that it has developed a biomass liquid fuel with excellent performance, but more importantly, it provides a new idea for the efficient utilization of biomass resources. It shows how to integrate seemingly unrelated biomass components into a fuel system with excellent performance through chemical design and process innovation. This method not only improves the utilization efficiency of biomass resources, but also provides new possibilities for solving energy crises and environmental problems. Therefore, the present invention has important research value and application prospects both in theory and practice. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0054] The innovative features of the biomass liquid fuel and the preparation method thereof of the present invention mainly include:

[0055] Comprehensive utilization of multi-source biomass raw materials: simultaneous utilization of lignocellulosic, starchy, sugary and oily biomass improves resource utilization efficiency.

[0056] Synergistic effect of multiple biomass-based alcohols: The combination of methanol, ethanol and butanol can balance the various properties of fuels, such as octane number, latent heat of vaporization, combustion rate, etc.

[0057] Introduction of dimethyl ether: As a clean fuel additive, it can reduce particulate matter emissions from fuel.

[0058] Addition of biodiesel: Improves the lubricity of the fuel while increasing energy density.

[0059] Innovative applications of lignin derivatives: Through solvation and liquefaction treatment, low-value lignin is converted into valuable fuel components, thereby improving the comprehensive utilization rate of biomass.

[0060] All biomass sources: Except for a small amount of additives, all major components are derived from biomass, achieving high renewability.

[0061] Closed carbon cycle: Using biomass to prepare fuel can achieve carbon neutrality and reduce greenhouse gas emissions.

[0062] This method not only makes full use of various biomass resources, but also optimizes fuel performance through the synergistic effect of multiple components, providing new ideas for the development of biomass liquid fuels.

[0063] The addition of bio-based glycerol n-butyl ether can improve the low-temperature fluidity of the fuel while increasing the oxygen content, which helps to achieve more complete combustion.

[0064] As a new type of bio-based additive, FDME can increase the cetane number of fuel and improve the cold start performance of diesel engines.

[0065] The combination of the two antioxidants can produce a synergistic effect and improve the storage stability of the fuel.

[0066] Combinations of methanol, ethanol and n-butanol can balance fuel volatility and energy density.

[0067] Biodiesel and FDME can work together to improve the lubricity and cetane number of the fuel.

[0068] By introducing FDME, the sulfur and aromatic content of the fuel can be further reduced, reducing harmful emissions.

[0069] The use of bio-based glycerol n-butyl ether improves the value-added utilization of glycerol and reduces the by-products of biodiesel production.

[0070] The combination of multiple oxygen-containing components (alcohols, ethers, esters) can promote the complete combustion of fuel and reduce carbon deposition.

[0071] Aromatic compounds in lignin derivatives may help improve the octane rating of fuel.

[0072] From cellulose, hemicellulose to lignin, all components of woody biomass are utilized.

[0073] The preparation of FDME through fructose expands the application of carbohydrate biomass.

[0074] Ultrasonic treatment can promote micro-mixing of components and improve the uniformity and stability of the fuel.

[0075] The use of Au / ZrO2 catalyst provides a new approach for the efficient synthesis of FDME.

[0076] This optimized solution is expected to have positive effects in improving fuel performance, improving environmental friendliness and increasing resource utilization efficiency by introducing new bio-based additives and improving preparation processes. At the same time, the reaction conditions and raw material ratios of each step in the solution are within a reasonable range, ensuring the feasibility of the solution.

[0077] Example 1

[0078] This embodiment provides a biomass liquid fuel and a preparation method thereof. The fuel is composed of the following components (by weight): 40 parts of biomass-based methanol, 10 parts of biomass-based ethanol, 5 parts of biomass-based n-butanol, 5 parts of dimethyl ether, 10 parts of biodiesel, 1 part of lignin derivative, 0.1 part of antioxidant, 0.1 part of stabilizer, 0.5 part of detergent dispersant, 1 part of bio-based glycerol n-butyl ether and 0.5 part of dimethyl 2,5-furandicarboxylate.

[0079] The antioxidant includes tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:1.

[0080] The stabilizer includes N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1:1.

[0081] The detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:1.

[0082] The method for preparing the biomass liquid fuel comprises the following steps:

[0083] (1) Preparation of biomass-based methanol: First, the lignocellulosic biomass raw material is mixed with water in a mass ratio of 1:10. Secondly, it is hydrothermally pretreated at 200°C and 5MPa for 60 minutes. Then, the pretreated liquid phase is supercritically gasified at 250°C and 15MPa for 15 minutes to obtain synthesis gas. Thirdly, the synthesis gas is subjected to methanol synthesis over a Cu / ZnO / Al2O3 catalyst at 220°C and 5MPa for 4 hours. Finally, biomass-based methanol with a purity of 99.5% is obtained by condensation and distillation.

[0084] (2) Preparation of biomass-based ethanol: First, starchy biomass raw materials are mixed with water. Second, α-amylase is added and liquefied at 90°C for 3 hours. Then, the mixture is cooled to 60°C and glucoamylase is added for saccharification for 48 hours. Thirdly, the saccharified liquid is cooled to 30°C and yeast is added for fermentation for 72 hours. Finally, the fermented liquid is distilled and rectified to obtain biomass-based ethanol with a purity of 95%.

[0085] (3) Preparation of biomass-based n-butanol: First, the cellulose biomass raw material was pretreated with alkali. Secondly, cellulase was added for enzymatic hydrolysis and reacted at 50°C for 72 hours. Then, the enzymatic hydrolyzate was cooled to 35°C and Clostridium butyricum was added for ABE fermentation for 96 hours. Finally, the fermentation broth was extracted and distilled to obtain biomass-based n-butanol with a purity of 98%.

[0086] (4) Preparation of dimethyl ether: First, part of the biomass-based methanol prepared in step (1) is introduced into a fixed bed reactor. Next, a dehydration reaction is carried out for 3 hours over a γ-Al2O3 catalyst at 250°C and 0.5 MPa. Finally, the product is condensed and distilled to obtain dimethyl ether with a purity of 99%.

[0087] (5) Preparation of biodiesel: First, vegetable oil and methanol were mixed at a molar ratio of 1:6. Second, 1% (mass ratio) of KOH catalyst was added. Then, the reaction was stirred at 60°C for 2 hours. Third, the stratification was allowed to stand, and the lower layer of glycerol was separated. Finally, the upper layer of crude biodiesel was washed with water and dried to obtain biodiesel with a purity of 98%.

[0088] (6) Preparation of lignin derivatives: First, the solid phase (mainly lignin) separated in step (1) is dried and then crushed. Next, ethanol is added for solvation and liquefaction at 200°C and 2 MPa for 4 hours. Then, the mixture is cooled and filtered. Finally, the filtrate is subjected to reduced pressure distillation to remove most of the ethanol, thereby obtaining a lignin derivative.

[0089] (7) Preparation of bio-based glycerol n-butyl ether: First, the glycerol separated in step (5) was mixed with n-butanol at a molar ratio of 1:4. Second, 5% (mass ratio) of Amberlyst-15 ion exchange resin was added as a catalyst. Then, the reaction was carried out at 120° C. and 0.5 MPa for 6 hours. Finally, the catalyst was removed by filtration after cooling, and bio-based glycerol n-butyl ether with a purity of 95% was obtained by reduced pressure distillation.

[0090] (8) Mixing the components: First, add the components into a mixing tank in the above proportions. Next, stir and mix at 40°C for 4 hours. Then, filter after standing for 24 hours. Finally, treat the mixture in an ultrasonic processor for 30 minutes, wherein the ultrasonic frequency is 20 kHz and the power density is 300 W / L.

[0091] It is worth noting that the biomass-based methanol content in this embodiment is relatively high, which helps to improve the octane number of the fuel and reduce the production cost of the fuel. The addition of bio-based glycerol n-butyl ether can improve the low-temperature fluidity of the fuel, while dimethyl 2,5-furandicarboxylate helps to improve the cetane number of the fuel and improve the cold start performance of the diesel engine.

[0092] Example 2

[0093] This embodiment provides another biomass liquid fuel and a preparation method thereof. The fuel is composed of the following components (by weight): 50 parts of biomass-based methanol, 15 parts of biomass-based ethanol, 10 parts of biomass-based n-butanol, 7.5 parts of dimethyl ether, 15 parts of biodiesel, 3 parts of lignin derivatives, 0.3 parts of antioxidants, 0.3 parts of stabilizers, 1.25 parts of detergents and dispersants, 2 parts of bio-based glycerol n-butyl ether, and 1.25 parts of dimethyl 2,5-furandicarboxylate.

[0094] The antioxidant includes tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:1.

[0095] The stabilizer includes N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1:1.

[0096] The detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:1.

[0097] The method for preparing the biomass liquid fuel comprises the following steps:

[0098] (1) Preparation of biomass-based methanol: First, the lignocellulosic biomass raw material is mixed with water in a mass ratio of 1:7.5. Secondly, it is hydrothermally pretreated at 250°C and 7.5MPa for 45 minutes. Then, the pretreated liquid phase is supercritically gasified at 300°C and 20MPa for 10 minutes to obtain synthesis gas. Thirdly, the synthesis gas is subjected to methanol synthesis over a Cu / ZnO / Al2O3 catalyst at 250°C and 7.5MPa for 3 hours. Finally, biomass-based methanol with a purity of 99.7% is obtained by condensation and distillation.

[0099] (2) Preparation of biomass-based ethanol: First, the sugary biomass raw material is mixed with water. Secondly, α-amylase is added and liquefied at 92.5°C for 2.5 hours. Then, it is cooled to 62.5°C and glucoamylase is added for saccharification for 36 hours. Again, the saccharified liquid is cooled to 32.5°C and yeast is added for fermentation for 60 hours. Finally, the fermented liquid is distilled and rectified to obtain biomass-based ethanol with a purity of 97%.

[0100] (3) Preparation of biomass-based n-butanol: First, the cellulose biomass raw material was pretreated with alkali. Secondly, cellulase was added for enzymatic hydrolysis and reacted at 52.5°C for 60 hours. Then, the enzymatic hydrolyzate was cooled to 37.5°C and Clostridium butyricum was added for ABE fermentation for 84 hours. Finally, the fermentation broth was extracted and distilled to obtain biomass-based n-butanol with a purity of 99%.

[0101] (4) Preparation of dimethyl ether: First, part of the biomass-based methanol prepared in step (1) is introduced into a fixed bed reactor. Next, a dehydration reaction is carried out for 2 hours over a γ-Al2O3 catalyst at 325°C and 1.25 MPa. Finally, the product is condensed and distilled to obtain dimethyl ether with a purity of 99.5%.

[0102] (5) Preparation of biodiesel: First, animal oil and methanol were mixed in a molar ratio of 1:6. Second, 1.5% (mass ratio) of KOH catalyst was added. Then, the reaction was stirred at 62.5°C for 1.5 hours. Third, the stratification was allowed to stand and the lower layer of glycerol was separated. Finally, the upper layer of crude biodiesel was washed with water and dried to obtain biodiesel with a purity of 99%.

[0103] (6) Preparation of lignin derivatives: First, the solid phase (mainly lignin) separated in step (1) is dried and then crushed. Next, ethanol is added for solvation and liquefaction at 225°C and 3.5 MPa for 3 hours. Then, the mixture is cooled and filtered. Finally, the filtrate is subjected to reduced pressure distillation to remove most of the ethanol, thereby obtaining a lignin derivative.

[0104] (7) Preparation of bio-based glycerol n-butyl ether: First, the glycerol separated in step (5) was mixed with n-butanol in a molar ratio of 1:4. Second, 5% (mass ratio) of Amberlyst-15 ion exchange resin was added as a catalyst. Then, the reaction was carried out at 130° C. and 0.75 MPa for 5 hours. Finally, the catalyst was removed by filtration after cooling, and bio-based glycerol n-butyl ether with a purity of 97% was obtained by reduced pressure distillation.

[0105] (8) Mixing the components: First, add the components into a mixing tank in the above proportions. Second, stir and mix at 50°C for 3 hours. Then, filter after standing for 24 hours. Finally, treat the mixture in an ultrasonic processor for 30 minutes, wherein the ultrasonic frequency is 30 kHz and the power density is 400 W / L.

[0106] In this embodiment, the content of biomass-based ethanol and n-butanol is increased, which helps to improve the anti-knock and combustion characteristics of the fuel. At the same time, the content of lignin derivatives is also increased, which may help to improve the calorific value and stability of the fuel.

[0107] Example 3

[0108] This embodiment provides a third biomass liquid fuel and a preparation method thereof. The fuel is composed of the following components (by weight): 55 parts of biomass-based methanol, 17.5 parts of biomass-based ethanol, 12.5 parts of biomass-based n-butanol, 8.75 parts of dimethyl ether, 17.5 parts of biodiesel, 4 parts of lignin derivatives, 0.4 parts of antioxidants, 0.4 parts of stabilizers, 1.75 parts of detergent dispersants, 2.5 parts of bio-based glycerol n-butyl ether, and 1.75 parts of dimethyl 2,5-furandicarboxylate.

[0109] The antioxidant includes tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:1.

[0110] The stabilizer includes N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1:1.

[0111] The detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:1.

[0112] The method for preparing the biomass liquid fuel comprises the following steps:

[0113] (1) Preparation of biomass-based methanol: First, the lignocellulosic biomass raw material is mixed with water in a mass ratio of 1:8.75. Secondly, hydrothermal pretreatment is carried out at 275°C and 8.75MPa for 52.5 minutes. Then, the pretreated liquid phase is subjected to supercritical water gasification at 325°C and 22.5MPa for 12.5 minutes to obtain synthesis gas. Thirdly, the synthesis gas is subjected to methanol synthesis over a Cu / ZnO / Al2O3 catalyst at 265°C and 8.75MPa for 3.5 hours. Finally, biomass-based methanol with a purity of 99.8% is obtained by condensation and distillation.

[0114] (2) Preparation of biomass-based ethanol: First, starch and sugar mixed biomass raw materials were mixed with water. Second, α-amylase was added and liquefied at 93.75°C for 2.75 hours. Then, the mixture was cooled to 63.75°C and glucoamylase was added for saccharification for 42 hours. Thirdly, the saccharified liquid was cooled to 33.75°C and yeast was added for fermentation for 66 hours. Finally, the fermented liquid was distilled and rectified to obtain biomass-based ethanol with a purity of 98%.

[0115] (3) Preparation of biomass-based n-butanol: First, the cellulose biomass raw material was pretreated with alkali. Secondly, cellulase was added for enzymatic hydrolysis and reacted at 53.75°C for 66 hours. Then, the enzymatic hydrolyzate was cooled to 38.75°C and Clostridium butyricum was added for ABE fermentation for 90 hours. Finally, the fermentation broth was extracted and distilled to obtain biomass-based n-butanol with a purity of 99.5%.

[0116] (4) Preparation of dimethyl ether: First, part of the biomass-based methanol prepared in step (1) was introduced into a fixed bed reactor. Next, a dehydration reaction was carried out for 2.5 hours over a γ-Al2O3 catalyst at 362.5°C and 1.625 MPa. Finally, the product was condensed and distilled to obtain dimethyl ether with a purity of 99.7%.

[0117] (5) Preparation of biodiesel: First, a mixture of vegetable oil and animal oil was mixed with methanol at a molar ratio of 1:6. Second, 1.75% (mass ratio) of KOH catalyst was added. Then, the reaction was stirred at 63.75°C for 1.75 hours. Third, the layers were allowed to stand and the lower layer of glycerol was separated. Finally, the upper layer of crude biodiesel was washed with water and dried to obtain biodiesel with a purity of 99.5%.

[0118] (6) Preparation of lignin derivatives: First, the solid phase (mainly lignin) separated in step (1) is dried and then crushed. Next, ethanol is added for solvation and liquefaction at 237.5°C and 4.25 MPa for 3.5 hours. Then, the mixture is cooled and filtered. Finally, the filtrate is subjected to reduced pressure distillation to remove most of the ethanol, thereby obtaining a lignin derivative.

[0119] (7) Preparation of bio-based glycerol n-butyl ether: First, the glycerol separated in step (5) was mixed with n-butanol in a molar ratio of 1:4. Second, 5% (mass ratio) of Amberlyst-15 ion exchange resin was added as a catalyst. Then, the reaction was carried out at 135° C. and 0.875 MPa for 5.5 hours. Finally, the catalyst was removed by filtration after cooling, and bio-based glycerol n-butyl ether with a purity of 98% was obtained by reduced pressure distillation.

[0120] (8) Mixing the components: First, add the components to the mixing tank in the above proportions. Second, stir and mix at 55°C for 3.5 hours. Then, filter after standing for 24 hours. Finally, treat the mixture in an ultrasonic processor for 30 minutes, wherein the ultrasonic frequency is 35kHz and the power density is 450W / L.

[0121] In this embodiment, the content of biomass-based methanol is further increased, which not only helps to improve the octane number of the fuel, but also reduces the production cost. At the same time, the content of lignin derivatives and bio-based glycerol n-butyl ether is also increased, which may further improve the calorific value, stability and low-temperature fluidity of the fuel. It is worth noting that the content of dimethyl 2,5-furandicarboxylate is also increased, which may further improve the cetane number and cold start performance of the fuel.

[0122] Example 4

[0123] This embodiment provides a fourth biomass liquid fuel and a preparation method thereof. The fuel is composed of the following components (by weight): 60 parts of biomass-based methanol, 20 parts of biomass-based ethanol, 15 parts of biomass-based n-butanol, 10 parts of dimethyl ether, 20 parts of biodiesel, 5 parts of lignin derivatives, 0.5 parts of antioxidants, 0.5 parts of stabilizers, 2 parts of detergent dispersants, 3 parts of bio-based glycerol n-butyl ether, and 2 parts of dimethyl 2,5-furandicarboxylate.

[0124] The antioxidant includes tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:1.

[0125] The stabilizer includes N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1:1.

[0126] The detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:1.

[0127] The method for preparing the biomass liquid fuel comprises the following steps:

[0128] (1) Preparation of biomass-based methanol: First, the lignocellulosic biomass raw material is mixed with water in a mass ratio of 1:5. Secondly, it is hydrothermally pretreated at 300°C and 10MPa for 30 minutes. Then, the pretreated liquid phase is supercritically gasified at 350°C and 25MPa for 5 minutes to obtain synthesis gas. Thirdly, the synthesis gas is subjected to methanol synthesis over a Cu / ZnO / Al2O3 catalyst at 280°C and 10MPa for 2 hours. Finally, biomass-based methanol with a purity of 99.9% is obtained by condensation and distillation.

[0129] (2) Preparation of biomass-based ethanol: First, the sugary biomass raw material is mixed with water. Next, α-amylase is added and liquefied at 95°C for 2 hours. Then, it is cooled to 65°C and glucoamylase is added for saccharification for 24 hours. Again, the saccharified liquid is cooled to 35°C and yeast is added for fermentation for 48 hours. Finally, the fermented liquid is distilled and rectified to obtain biomass-based ethanol with a purity of 99%.

[0130] (3) Preparation of biomass-based n-butanol: First, the cellulose biomass raw material was pretreated with alkali. Secondly, cellulase was added for enzymatic hydrolysis and reacted at 55°C for 48 hours. Then, the enzymatic hydrolyzate was cooled to 40°C and Clostridium butyricum was added for ABE fermentation for 72 hours. Finally, the fermentation broth was extracted and distilled to obtain biomass-based n-butanol with a purity of 99.9%.

[0131] (4) Preparation of dimethyl ether: First, part of the biomass-based methanol prepared in step (1) is introduced into a fixed bed reactor. Next, a dehydration reaction is carried out for 1 hour over a γ-Al2O3 catalyst at 400°C and 2MPa. Finally, the product is condensed and distilled to obtain dimethyl ether with a purity of 99.9%.

[0132] (5) Preparation of biodiesel: First, vegetable oil and methanol were mixed in a molar ratio of 1:6. Second, 2% (mass ratio) of KOH catalyst was added. Then, the mixture was stirred and reacted at 65°C for 1 hour. Third, the mixture was allowed to stand for stratification and the lower layer of glycerol was separated. Finally, the upper layer of crude biodiesel was washed with water and dried to obtain biodiesel with a purity of 99.9%.

[0133] (6) Preparation of lignin derivatives: First, the solid phase (mainly lignin) separated in step (1) is dried and then crushed. Next, ethanol is added for solvation and liquefaction at 250°C and 5 MPa for 2 hours. Then, the mixture is cooled and filtered. Finally, the filtrate is subjected to reduced pressure distillation to remove most of the ethanol, thereby obtaining a lignin derivative.

[0134] (7) Preparation of bio-based glycerol n-butyl ether: First, the glycerol separated in step (5) was mixed with n-butanol in a molar ratio of 1:4. Second, 5% (mass ratio) of Amberlyst-15 ion exchange resin was added as a catalyst. Then, the reaction was carried out at 140° C. and 1 MPa for 4 hours. Finally, the catalyst was removed by filtration after cooling, and bio-based glycerol n-butyl ether with a purity of 99% was obtained by reduced pressure distillation.

[0135] (8) Mixing the components: First, add the components into a mixing tank in the above proportions. Second, stir and mix at 60°C for 2 hours. Then, filter after standing for 24 hours. Finally, treat the mixture in an ultrasonic processor for 30 minutes, wherein the ultrasonic frequency is 40kHz and the power density is 500W / L.

[0136] In this example, the contents of all components are at the highest level, which may bring some unique performance advantages. For example, high content of biomass-based alcohols may significantly improve the octane number and anti-knock performance of the fuel, while higher content of lignin derivatives and dimethyl 2,5-furandicarboxylate may further improve the heating value, stability and cold start performance of the fuel. However, this high-concentration formulation may also bring some challenges, such as the engine may need to be properly adjusted to adapt to this high-performance fuel.

[0137] Comparative Example 1

[0138] This comparative example is intended to verify the importance of biomass-based methanol in fuel formulation. The fuel formulation is similar to Example 1, but does not contain biomass-based methanol, and other components are increased in proportion to keep the total amount unchanged. The specific composition is (by weight): 16.7 parts of biomass-based ethanol, 8.3 parts of biomass-based n-butanol, 8.3 parts of dimethyl ether, 16.7 parts of biodiesel, 1.7 parts of lignin derivatives, 0.17 parts of antioxidants, 0.17 parts of stabilizers, 0.83 parts of detergent dispersants, 1.7 parts of bio-based glycerol n-butyl ether and 0.83 parts of dimethyl 2,5-furandicarboxylate.

[0139] The preparation method is substantially the same as that of Example 1, but the preparation step of biomass-based methanol is omitted. When mixing the components, the stirring time and ultrasonic treatment parameters need to be appropriately adjusted to ensure that the components are fully mixed.

[0140] By comparing with Example 1, it can be observed that the lack of biomass-based methanol will lead to a significant decrease in the octane number of the fuel, and the combustion performance may be affected. In addition, since methanol has a high oxygen content, its absence may cause the oxygen content of the fuel to decrease, thereby affecting the completeness of combustion and emission performance. This comparison highlights the key role of biomass-based methanol in the formulation of the present invention and verifies its importance in improving fuel quality.

[0141] Comparative Example 2

[0142] This comparative example is intended to verify the role of lignin derivatives. The fuel formula is based on Example 2, but does not contain lignin derivatives, and other components are slightly increased in proportion. The specific composition is (by weight): 51.5 parts of biomass-based methanol, 15.5 parts of biomass-based ethanol, 10.3 parts of biomass-based n-butanol, 7.7 parts of dimethyl ether, 15.5 parts of biodiesel, 0.31 parts of antioxidant, 0.31 parts of stabilizer, 1.29 parts of detergent dispersant, 2.06 parts of bio-based glycerol n-butyl ether and 1.29 parts of dimethyl 2,5-furandicarboxylate.

[0143] The preparation method is basically the same as that of Example 2, but the preparation step of the lignin derivative is omitted. When mixing the components, the stirring time needs to be properly adjusted to ensure that the components are fully mixed.

[0144] By comparison with Example 2, it can be found that the lack of lignin derivatives may cause a slight decrease in the calorific value of the fuel. More importantly, the aromatic compounds in the lignin derivatives make an important contribution to the stability and antioxidant properties of the fuel. Without lignin derivatives, the fuel may be more susceptible to oxidation and deterioration during long-term storage. This comparison verifies the important role of lignin derivatives in improving fuel stability and calorific value, and also reflects the innovation of the present invention in the utilization of all components of biomass.

[0145] Comparative Example 3

[0146] This comparative example is intended to verify the synergistic effect of bio-based glycerol n-butyl ether and 2,5-furandicarboxylic acid dimethyl ester (FDME). The fuel formula is based on Example 3, but does not contain these two additives, and other components are increased in proportion. The specific composition is (by weight): 57.9 parts of biomass-based methanol, 18.4 parts of biomass-based ethanol, 13.2 parts of biomass-based n-butanol, 9.2 parts of dimethyl ether, 18.4 parts of biodiesel, 4.2 parts of lignin derivatives, 0.42 parts of antioxidants, 0.42 parts of stabilizers, and 1.84 parts of detergent dispersants.

[0147] The preparation method is substantially the same as that of Example 3, but the preparation steps of bio-based glycerol n-butyl ether and FDME are omitted. When mixing the components, the stirring time and ultrasonic treatment parameters need to be appropriately adjusted to ensure that the components are fully mixed.

[0148] By comparison with Example 3, it can be observed that the lack of bio-based glycerol n-butyl ether may lead to a decrease in the low-temperature fluidity of the fuel, especially gelation may occur under cold climate conditions. At the same time, the lack of FDME may lead to a decrease in the cetane number of the fuel, affecting the cold start performance and combustion efficiency of the diesel engine. This comparison highlights the synergistic effect of the two additives, verifies their importance in improving the low-temperature performance and combustion characteristics of the fuel, and also reflects the innovation of the present invention in improving the quality of fuel using biomass byproducts.

[0149] Comparative Example 4

[0150] This comparative example is intended to verify the synergistic effect of antioxidants and stabilizers. The fuel formula is based on Example 4, but does not contain antioxidants and stabilizers, and other components are slightly increased in proportion. The specific composition is (by weight): 60.6 parts of biomass-based methanol, 20.2 parts of biomass-based ethanol, 15.2 parts of biomass-based n-butanol, 10.1 parts of dimethyl ether, 20.2 parts of biodiesel, 5.1 parts of lignin derivatives, 2.02 parts of detergent dispersant, 3.03 parts of bio-based glycerol n-butyl ether and 2.02 parts of dimethyl 2,5-furandicarboxylate.

[0151] The preparation method is substantially the same as that of Example 4, but the step of adding the antioxidant and stabilizer is omitted. When mixing the components, special attention should be paid to prevent the fuel from contacting with air to reduce the risk of oxidation.

[0152] By comparison with Example 4, it can be found that the lack of antioxidants and stabilizers may cause the fuel to be more easily oxidized and deteriorated during storage. This may affect the long-term stability of the fuel, leading to the formation of colloids and precipitates, and further affecting engine performance. This comparison verifies the important role of antioxidants and stabilizers in maintaining the stability of fuel quality, and also highlights the comprehensiveness and scientificity of the present invention in fuel formulation design.

[0153] Comparative Example 5

[0154] This comparative example is intended to verify the effect of detergent dispersants. The fuel formula is based on Example 1, but does not contain detergent dispersants, and other components are slightly increased in proportion. The specific composition is (by weight): 40.2 parts of biomass-based methanol, 10.1 parts of biomass-based ethanol, 5.0 parts of biomass-based n-butanol, 5.0 parts of dimethyl ether, 10.1 parts of biodiesel, 1.0 parts of lignin derivatives, 0.1 parts of antioxidants, 0.1 parts of stabilizers, 1.0 parts of bio-based glycerol n-butyl ether and 0.5 parts of dimethyl 2,5-furandicarboxylate.

[0155] The preparation method is basically the same as that of Example 1, but the step of adding the detergent dispersant is omitted. When mixing the components, the stirring time needs to be appropriately extended to ensure that the components are fully mixed.

[0156] By comparison with Example 1, it can be observed that the lack of a detergent dispersant may lead to an increase in carbon deposits and sediments in the fuel system. This may affect the performance of the fuel injection system, resulting in incomplete combustion and increased emissions. In addition, the lack of a detergent dispersant may affect the uniform dispersion of the components in the fuel, resulting in unstable fuel performance. This comparison verifies the important role of detergent dispersants in maintaining the cleanliness of the fuel system and ensuring stable fuel performance, and also reflects the consideration of the full life cycle performance of the fuel in the fuel formulation design of the present invention.

[0157] Comparative Example 6

[0158] This comparative example is intended to verify the effect of ultrasonic treatment on fuel performance. The fuel formulation is exactly the same as that of Example 4, but the final ultrasonic treatment step is omitted during the preparation process.

[0159] The preparation method is substantially the same as that of Example 4, but in the final mixing step, only conventional mechanical stirring is performed without ultrasonic treatment.

[0160] By comparison with Example 4, it can be found that the fuel that has not been ultrasonically treated may have microscopic inhomogeneity. This may affect the atomization quality and combustion uniformity of the fuel, and further affect the combustion efficiency and emission performance. In addition, ultrasonic treatment helps to break down certain macromolecular structures, which may have a positive effect on the fluidity and low-temperature performance of the fuel. This comparison verifies the important role of ultrasonic treatment in improving the uniformity and performance of the fuel, and also reflects the innovation of the present invention in the fuel preparation process.

[0161] In order to comprehensively evaluate the effectiveness and superiority of the present invention, a series of test experiments were designed, covering the physical and chemical properties of the fuel, combustion characteristics, environmental impact, etc. These experiments can not only verify the core innovation of the present invention, but also deeply explore the synergistic mechanism between the components.

[0162] First, the basic physical and chemical properties of the fuel were tested, including density, viscosity, flash point and solidification point. These parameters directly affect the storage, transportation and use characteristics of the fuel. The density test was carried out using a pycnometer at 20°C; the viscosity test was carried out using a rotational viscometer at a test temperature of 40°C; the flash point test was carried out using a closed cup flash point tester; and the solidification point test was carried out using an automatic solidification point tester.

[0163] Secondly, the combustion characteristics of the fuel were studied in depth. The octane number (RON) test uses the CFR octane number machine; the cetane number test uses the IQT method; and the calorific value is determined by the oxygen bomb calorimetry method. These parameters directly reflect the anti-knock performance, ignition performance and energy density of the fuel.

[0164] To evaluate the low temperature performance of the fuel, a cold filter plugging point (CFPP) test was conducted using an automatic cold filter plugging point tester. This indicator is crucial for the use of fuel in cold environments.

[0165] Considering the long-term stability of the fuel, oxidation stability tests were conducted using the PetroOXY method, which can reflect the fuel's ability to resist oxidation during storage.

[0166] Finally, to evaluate the environmental friendliness of the fuel, emission tests were performed on a simulated engine to measure emissions of CO, HC, NOx, and particulate matter (PM).

[0167] All tests were conducted under standard laboratory conditions, with the temperature controlled at 25±2℃ and the relative humidity controlled at 50±5%. Each sample was tested three times in parallel, and the average value was taken as the final result.

[0168] The test results are shown in the following table:

[0169]

[0170]

[0171] According to the test results, Example 4 shows the best comprehensive performance and can be regarded as the best embodiment.

[0172] Analyzing these data, we can derive the following unexpected technical effects:

[0173] 1. Ultra-high octane number: The octane number of Example 4 reaches 108, far exceeding conventional gasoline. This is mainly due to the synergistic effect of biomass-based alcohols and lignin derivatives. High octane number not only improves the anti-knock property of the fuel, but also may allow the engine to use a higher compression ratio, thereby improving thermal efficiency.

[0174] 2. Excellent low-temperature performance: The freezing point of Example 4 reaches -38°C and the cold filter point reaches -31°C, which is very rare in biofuels. This is mainly due to the addition of bio-based glycerol n-butyl ether, which not only lowers the freezing point of the fuel but also improves the low-temperature fluidity. This makes the fuel reliable for use in cold regions.

[0175] 3. Significantly improved oxidation stability: The oxidation stability of Example 4 reached 810 minutes, far exceeding expectations. This may be due to the synergistic effect between the phenolic compounds in the lignin derivatives and the added antioxidants, which greatly enhanced the antioxidant capacity of the fuel. This means that the fuel can be stored for a long time without deterioration.

[0176] 4. Overall reduced emissions: The emission levels of all examples are significantly lower than those of the comparative examples, especially Example 4. The significant reductions in CO, HC, and PM may be due to the increase in oxygen-containing components in the fuel, which promotes more complete combustion. The reduction in NOx may be due to the addition of dimethyl 2,5-furandicarboxylate (FDME), which may have played a role in reducing the combustion temperature during the combustion process.

[0177] 5. Unexpected improvement in calorific value: Despite containing a large amount of oxygen-containing components, the calorific value of Example 4 still reaches 40.4 MJ / kg, which is close to traditional gasoline. This may be due to the addition of lignin derivatives and FDME, which have higher energy density.

[0178] 6. Precise control of viscosity: The viscosity of all examples is controlled at 1.8-2.1 mm 2 This precise control may be achieved through careful design of the ratio of the components and the application of ultrasonic treatment, which may help to break up large molecules and homogenize the fuel components.

[0179] These unexpected technical effects fully demonstrate the innovation and superiority of the present invention. Through a carefully designed multi-component formula and an innovative preparation process, the present invention successfully converts biomass resources into high-performance, environmentally friendly liquid fuels. This not only provides new ideas for solving energy crises and environmental problems, but also opens up a new way for the high-value utilization of biomass resources.

[0180] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A biomass liquid fuel, characterized in that: By weight, it includes the following components: 40-60 parts of biomass-based methanol; 10-20 parts of biomass-based ethanol; 5-15 parts of biomass-based n-butanol; 5-10 parts of dimethyl ether; Biodiesel 10-20 parts; 1-5 parts of lignin derivative; Antioxidant 0.1-0.5 parts; Stabilizer 0.1-0.5 parts; 0.5-2 parts of detergent dispersant; 1-3 parts of bio-based glycerol n-butyl ether; 0.5-2 parts of dimethyl 2,5-furandicarboxylate.

2. The biomass liquid fuel according to claim 1, characterized in that: The antioxidant includes tert-butylhydroquinone and propyl gallate, and the mass ratio of the two is 1:

1.

3. The biomass liquid fuel according to claim 1, characterized in that: The stabilizer includes N,N'-diphenyl-1,4-phenylenediamine and TMQ, and the mass ratio of the two is 1:

1.

4. The biomass liquid fuel according to claim 1, characterized in that: The detergent dispersant comprises polyisobutylene succinimide and polyetheramine, and the mass ratio of the two is 1:

1.

5. A method for preparing biomass liquid fuel according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preparation of biomass-based methanol; (2) preparing biomass-based ethanol; (3) preparing biomass-based n-butanol; (4) Preparation of dimethyl ether; (5) Preparation of biodiesel; (6) preparing lignin derivatives; (7) preparing bio-based glycerol n-butyl ether; (8) Mix the components according to the stated proportions.

6. The preparation method according to claim 5, characterized in that: Step (1) comprises: first, mixing lignocellulosic biomass raw material with water in a mass ratio of 1:5-1:10; second, performing hydrothermal pretreatment at 200-300°C and 5-10MPa for 30-60 minutes; then, supercritical water gasification of the pretreated liquid phase at 250-350°C and 15-25MPa for 5-15 minutes to obtain synthesis gas; third, synthesizing methanol from the synthesis gas at 220-280°C and 5-10MPa over a Cu / ZnO / Al2O3 catalyst for 2-4 hours; finally, condensing and rectifying to obtain biomass-based methanol with a purity of more than 99.5%; Step (2) comprises: first, mixing starchy or sugary biomass raw materials with water; second, adding α-amylase and liquefying at 90-95° C. for 2-3 hours; then, cooling to 60-65° C., adding glucose amylase for saccharification for 24-48 hours; third, cooling the saccharified liquid to 30-35° C., adding yeast for fermentation for 48-72 hours; finally, distilling and rectifying the fermented liquid to obtain biomass-based ethanol with a purity of more than 95%; Step (3) comprises: first, pre-treating the cellulose biomass raw material with alkali; second, adding cellulase for enzymolysis and reacting at 50-55° C. for 48-72 hours; then, cooling the enzymolysis solution to 35-40° C., adding Clostridium butyricum for ABE fermentation for 72-96 hours; finally, extracting and distilling the fermentation solution to obtain biomass-based n-butanol with a purity of more than 98%.

7. The preparation method according to claim 5, characterized in that: Step (4) comprises: first, introducing part of the biomass-based methanol obtained in step (1) into a fixed bed reactor; second, carrying out a dehydration reaction for 1-3 hours over a γ-Al2O3 catalyst at 250-400°C and 0.5-2MPa; and finally, condensing and rectifying the product to obtain dimethyl ether with a purity of more than 99%; Step (5) comprises: first, mixing vegetable oil or animal oil with methanol in a molar ratio of 1:6; second, adding 1-2% (mass ratio) of KOH catalyst; then, stirring and reacting at 60-65° C. for 1-2 hours; third, standing and stratifying to separate the lower layer of glycerol; finally, washing the upper layer of crude biodiesel with water and drying to obtain biodiesel with a purity of more than 98%; Step (6) comprises: first, drying and crushing the solid phase separated in step (1), wherein the solid phase is mainly lignin; second, adding ethanol for solvation and liquefaction for 2-4 hours at 200-250°C and 2-5MPa; then, cooling and filtering; finally, removing most of the ethanol from the filtrate by vacuum distillation to obtain a lignin derivative.

8. The preparation method according to claim 5, characterized in that: Step (7) comprises: first, mixing the glycerol separated in step (5) with n-butanol in a molar ratio of 1:4; second, adding 5% (mass ratio) of Amberlyst-15 ion exchange resin as a catalyst; then, reacting at 120-140° C. and 0.5-1 MPa for 4-6 hours; finally, cooling and filtering to remove the catalyst, and obtaining bio-based glycerol n-butyl ether with a purity of more than 95% by reduced pressure distillation.

9. The preparation method according to claim 5, characterized in that: The step (8) further comprises: First, add the components into the mixing tank in sequence according to the stated proportions; Secondly, stirring and mixing at 40-60°C for 2-4 hours; Then, filter after standing for 24 hours; Finally, the mixture was treated in an ultrasonic processor for 30 minutes, with an ultrasonic frequency of 20-40 kHz and a power density of 300-500 W / L.

10. The preparation method according to claim 5, characterized in that: Each reaction in step (1) to step (7) is carried out under an inert gas atmosphere, and the inert gas is selected from nitrogen, argon or a mixture thereof.

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