Method for preparing biomass fuel oil based on rosin waste oil

Abstract

The invention provides a method for preparing biomass fuel oil based on waste rosin oil, which comprises the following steps: pretreatment: filtering the waste rosin oil by using a 300-mesh filter screen to remove larger impurities, then adding a composite adsorbent A, stirring at 50-70 DEG C for 2-4 hours, and filtering to remove impurities; catalytic cracking: mixing the obtained product with a catalyst B, and reacting in two stages for 4-12 hours in total; refining: adding an additive C into the obtained cracking product, stirring for 1-2 hours at 60-80 DEG C under the protection of nitrogen, and performing membrane filtration to obtain biomass fuel oil; the composite adsorbent A is prepared from activated clay, nano silicon dioxide and sodium carboxymethyl cellulose; the additive C is prepared from polyoxymethylene dimethyl ether and 2-ethylhexyl nitrate. Through composite adsorption, two-stage catalytic cracking and additive compounding, the rosin waste oil is efficiently converted into biomass fuel oil reaching the standard, the catalyst cost is remarkably reduced, the process energy consumption is greatly reduced, and the environment-friendly production requirement is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass energy and renewable energy, and particularly relates to a method for preparing biomass fuel from waste rosin oil. Background Art

[0002] Waste rosin oil is a by-product generated during the production and processing of rosin. It mainly consists of oxidized rosin acid, polymeric resin acid, neutral non-saponifiable matter and a small amount of water, and has the characteristics of high viscosity, high acid value (>150 mg KOH / g) and low calorific value (<35 MJ / kg). Traditional treatment methods include direct incineration or simple distillation, but there are the following problems: 1. Resource waste: The effective components (such as resin acid) in waste rosin oil are not fully utilized, and direct incineration leads to energy waste and carbon dioxide emissions.

[0003] 2. Poor product performance: The fuel obtained by the conventional distillation method has a high viscosity (>60 mm 2 / s) and a low flash point (<70°C), which cannot meet the diesel fuel standard (GB 19147).

[0004] 3. High process cost: The existing catalytic cracking technology needs to use noble metal catalysts (such as platinum / alumina, cost >5000 yuan / kg), and the reaction conditions are harsh (pressure >3 MPa, temperature >400°C).

[0005] In view of these problems, the existing technology uses centrifugal separation or acid washing to remove impurities, but the treatment efficiency is low and secondary pollution is generated. Using a single molecular sieve catalyst (such as HZSM-5) to improve the cracking efficiency, but the catalyst is easily deactivated. Adding antioxidants to delay oxidation, but the problem of insufficient calorific value is not solved.

[0006] Although the existing technology reduces resource waste to a certain extent, there are still disadvantages such as fast catalyst deactivation, single additive and low separation efficiency. For example, Chinese Patent CN107502392A discloses a method for preparing biomass fuel by recycling the distillate of waste rosin oil. However, it uses single activated carbon adsorption (particle size 0.5 - 1 mm) and a fixed catalyst dosage (5%), resulting in low adsorption efficiency (impurity residue >10%), and the calorific value of the product is only 38 MJ / kg. In addition, the existing technology does not solve the problems of poor fuel storage stability (stratification occurs within 3 months) and high sulfur content (>200 ppm).

[0007] Therefore, it is necessary to design a method for preparing biomass fuel from waste rosin oil. Summary of the Invention

[0008] In order to overcome the defects in the existing technology, a method for preparing biomass fuel from waste rosin oil is provided.

[0009] To achieve the above object, the present invention provides the following technical solutions: A method for preparing biomass fuel from waste rosin oil, the method comprising the following steps: (1) Pretreatment: Filter the waste rosin oil through a 300-mesh filter screen to remove larger impurities, then add composite adsorbent A, stir at 50 - 70 °C for 2 - 4 h, and filter to remove impurities; (2) Catalytic cracking: Mix the product obtained in step (1) with catalyst B, and react in two stages at 250 - 320 °C and 0.2 - 0.8 MPa for a total duration of 4 - 12 h; (3) Refining: Add additive C to the cracking product obtained in step (2), stir at 60 - 80 °C under nitrogen protection for 1 - 2 h, and obtain biomass fuel after membrane filtration; The composite adsorbent A includes activated clay, nano-silica, and sodium carboxymethyl cellulose; The additive C includes polyoxymethylene dimethyl ether and 2-ethylhexyl nitrate.

[0010] The composite adsorbent A is compounded from activated clay, nano-silica, and sodium carboxymethyl cellulose in a mass ratio of 3 - 5:2 - 4:1, and the dosage of the composite adsorbent A is 5 - 20% of the mass of the waste rosin oil.

[0011] The preparation method of the composite adsorbent A is as follows: (a) Mix acid-modified activated clay with nano-silica, add a 5% polyvinyl alcohol solution according to a solid-liquid ratio of 1:2 - 4, and ball mill for 2 h at a rotation speed of 300 rpm; (b) Add sodium carboxymethyl cellulose, spray dry at 60 °C, and pass through a 300-mesh sieve.

[0012] The activated clay is obtained by acid-modifying clay, and the specific steps and parameters are: Immerse the clay in a 10% wt sulfuric acid solution, with a mass ratio of clay to sulfuric acid solution of 1:4 - 6, stir at 80 °C for 2 h, wash to neutrality and then dry.

[0013] The catalyst B is a composite of Hβ zeolite and phosphotungstic acid, with a mass ratio of Hβ zeolite to phosphotungstic acid of 1:0.3 - 1.5, and the dosage of the catalyst B is 1 - 10% of the mass of the product obtained in step (1).

[0014] The Hβ zeolite needs to be hydrothermally modified before use, and the specific modification steps are: Place the Hβ zeolite in a high-pressure reaction kettle, add 10%wt ammonia water, with a mass ratio of Hβ zeolite to ammonia water of 2 - 4:1, treat at 150 °C for 6 h, and centrifuge and dry.

[0015] In the step (2), the reaction temperature in the first stage is 250 - 280 °C, the pressure is 0.2 - 0.5 MPa, and the duration is 2 - 5 h; In the second stage, the temperature is raised to 300 - 320 °C, the pressure is 0.5 - 0.8 MPa, and the duration is 2 - 7 h.

[0016] In the additive C, the mass ratio of polymethoxydimethylether to 2-ethylhexyl nitrate is 2 - 4:1.

[0017] The synthesis method of the additive C includes the following steps: Mix polymethoxydimethylether and 2-ethylhexyl nitrate to obtain a mixture, add dibutyltin dilaurate accounting for 0.4% - 0.6% of the mass of the mixture, react at 70 °C for 4 h, and distill to remove the unreacted substances to obtain the additive C.

[0018] In the step (3) as described above, membrane filtration is carried out by serial filtration of a ceramic membrane and a polyvinylidene fluoride membrane, and the operating pressure is 0.3 - 0.6 MPa.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. Through the synergistic effect of the composite adsorbent A, the present application realizes the efficient adsorption of gum, metal ions and free acid in rosin waste oil. After acid modification, the layer spacing of activated clay expands, and the specific surface area is increased to 200 - 250 m² / g. Nano-silica fills the pores, and sodium carboxymethylcellulose is used as a dispersant to prevent particle aggregation. The compounding of the three makes the adsorption efficiency more than 3 times higher than that of traditional activated carbon, and the impurity residue rate ≤ 2%. At the same time, the recovery rate of resin acid in the pretreated rosin waste oil ≥ 90%, the utilization rate of effective components is improved, and resource waste is avoided.

[0020] 2. The present application adopts a two-stage reaction process combined with a hydrothermally modified Hβ zeolite / tungstophosphoric acid composite catalyst, significantly reducing the reaction pressure to below 0.8 MPa. The modified Hβ zeolite removes framework aluminum through ammonia treatment to form a mesoporous structure. Tungstophosphoric acid serves as an acidic site to enhance the cracking activity. The compounding of the two extends the catalyst life to more than 200 hours and does not require precious metals. The proportion of C10 - C20 hydrocarbons in the cracking products ≥ 85%, the light components are reduced, and the fuel calorific value is increased to 42 - 45 MJ / kg, meeting the national standard diesel requirements, achieving double optimization of catalytic cracking efficiency and catalyst life.

[0021] 3. The compounding design of additive C solves the problems of poor oxidation stability and low cetane number of traditional biomass fuels. As an oxygen-containing component, polyoxymethylene dimethyl ether promotes complete combustion and reduces carbon deposition; 2-ethylhexyl nitrate is used as a cetane number improver to make the cetane number of the fuel ≥50. In addition, the ceramic membrane and the polyvinylidene fluoride membrane are filtered in series to remove residual gum and catalyst particles, and the fuel turbidity ≤0.5 NTU, and there is no delamination phenomenon after 6 months of storage, which significantly improves the fuel performance and storage stability.

[0022] 4. The composite adsorbent A uses cheap raw materials to replace traditional noble metal catalysts; the energy consumption of the two-stage cracking process is reduced by 30%; membrane filtration replaces high-energy-consuming distillation, and the water consumption is reduced by 40%. At the same time, there is no strong acid / strong base emission throughout the process, the waste gas is condensed and recycled to recover light oil, the wastewater COD ≤100 mg / L, and the sulfur content ≤50 ppm, meeting the requirements of green production, and the process cost and environmental protection advantages are prominent.

[0023] 5. Catalyst B can be repeatedly regenerated and used more than 5 times; the synthesis process of additive C is simple and does not require complex purification. The prepared biomass fuel can be directly used in diesel engines, with the PM emission in the exhaust gas ≤0.05 g / kWh and the NOx emission reduced by 15-20%, meeting the national VI emission standards, and the adaptability and industrialization potential are significant. Detailed implementation manners

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] In this application, the models of various raw materials are briefly described as follows: Activated clay: purchased from Hubei Jianghan Oilfield Fine Chemical Co., Ltd., model JH-BT01; Nano-silica: purchased from Zhejiang Yuda New Materials Co., Ltd. (Yuda Nano), particle size 10-20 nm, purity ≥99.5%; Sodium carboxymethyl cellulose (CMC-Na): purchased from Shanghai Macklin Biochemical Co., Ltd. (Macklin), degree of substitution 0.7-0.9, viscosity 800-1200 mPa·s; Hβ molecular sieve: purchased from Shandong Qilu Molecular Sieve Co., Ltd. (QL-Hβ-25), silicon-aluminum ratio 25:1, specific surface area 450-500 m 2 / g; Phosphotungstic acid (HPW): purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Aladdin), purity ≥99%; Polymethoxy dimethyl ether (PODE): Purchased from Shandong Yuhuang Chemical Co., Ltd. (Yuhuang), with an average degree of polymerization of 3 - 5 and an oxygen content of ≥45%; 2 - Ethylhexyl nitrate (EHN): Purchased from Jiaxing Zhong'an Chemical Co., Ltd. (Zhong'an), with a purity of ≥98%; Dibutyltin dilaurate: Purchased from Beijing J&K Scientific Ltd. (J&K), with a purity of ≥95%; Ceramic membrane: Purchased from Jiangsu Jiuwu Hi - tech Co., Ltd. (Jiuwu), with the material Al 2 O 3 , and the pore size is 0.1 μm; Polyvinylidene fluoride membrane (PVDF): Purchased from Solvay Group (Solvay) in the United States, model Solef® 5130, with a retention molecular weight of 10 kDa; Polyvinyl alcohol (PVA): Purchased from China National Petroleum and Chemical Corporation (Sinopec), with an alcoholysis degree of 88%; Sulfuric acid (H 2 SO 4 ): Purchased from Shanghai Chemical Reagent Co., Ltd. (SCRC), analytical pure, with a concentration of 98%, and diluted correspondingly during use; Ammonia water (NH 3 ·H 2 O): Purchased from Nanjing Chemical Reagent Co., Ltd. (NCRC), with a concentration of 25% - 28%.

[0026] A method for preparing biomass fuel based on rosin waste oil, the method comprising the following steps: (1) Pretreatment: Filter the rosin waste oil through a 300 - mesh sieve to remove larger impurities, then add composite adsorbent A, stir at 50 - 70 °C for 2 - 4 h, and filter to remove impurities; (2) Catalytic cracking: Mix the product obtained in step (1) with catalyst B, and react in two stages at 250 - 320 °C and 0.2 - 0.8 MPa for a total duration of 4 - 12 h; (3) Refining: Add additive C to the cracking product obtained in step (2), stir at 60 - 80 °C under nitrogen protection for 1 - 2 h, and obtain biomass fuel after membrane filtration; The composite adsorbent A includes activated clay, nano - silica, and sodium carboxymethylcellulose; The additive C includes polymethoxy dimethyl ether and 2 - ethylhexyl nitrate.

[0027] The composite adsorbent A is compounded from activated clay, nano - silica, and sodium carboxymethylcellulose according to a mass ratio of 3 - 5:2 - 4:1, and the dosage of the composite adsorbent A is 5 - 20% of the mass of the rosin waste oil.

[0028] The preparation method of the composite adsorbent A is as follows: (a)Mix acid-modified activated clay with nano-silica, add 5% polyvinyl alcohol solution according to the solid-liquid ratio of 1:2 - 4, ball mill for 2 h at a rotation speed of 300 rpm; (b)Add sodium carboxymethyl cellulose, spray dry at 60 °C, and pass through a 300-mesh sieve.

[0029] The activated clay is obtained by acid-modifying clay. The specific steps and parameters are as follows: Immerse the clay in a 10% wt sulfuric acid solution, with the mass ratio of clay to sulfuric acid solution being 1:4 - 6, stir at 80 °C for 2 h, wash until neutral and then dry.

[0030] The catalyst B is a composite of Hβ zeolite and phosphotungstic acid. The mass ratio of Hβ zeolite to phosphotungstic acid is 1:0.3 - 1.5, and the dosage of the catalyst B is 1 - 10% of the mass of the product obtained in step (1).

[0031] The Hβ zeolite needs to be hydrothermally modified before use. The specific modification steps are as follows: Place the Hβ zeolite in a high-pressure reaction kettle, add 10%wt ammonia water, with the mass ratio of Hβ zeolite to ammonia water being 2 - 4:1, treat at 150 °C for 6 h, and then centrifuge and dry.

[0032] In the step (2), the reaction temperature in the first stage is 250 - 280 °C, the pressure is 0.2 - 0.5 MPa, and the duration is 2 - 5 h; In the second stage, the temperature is raised to 300 - 320 °C, the pressure is 0.5 - 0.8 MPa, and the duration is 2 - 7 h.

[0033] In the additive C, the mass ratio of polymethoxydimethylether to 2-ethylhexyl nitrate is 2 - 4:1.

[0034] The synthesis method of the additive C includes the following steps: Mix polymethoxydimethylether with 2-ethylhexyl nitrate to obtain a mixture, add 0.4% - 0.6% of dibutyltin dilaurate based on the mass of the mixture, react at 70 °C for 4 h, and distill to remove the unreacted substances to obtain the additive C.

[0035] In the step (3), the membrane filtration adopts a series filtration of a ceramic membrane and a polyvinylidene fluoride membrane, and the operating pressure is 0.3 - 0.6 MPa.

[0036] The technical principle of some steps in this application is as follows: After the activated clay is modified by sulfuric acid, the layer spacing is enlarged, and the specific surface area is increased to 200 - 250 m² / g. Nano-silica (particle size 10 - 20 nm) fills the pores, and sodium carboxymethyl cellulose acts as a dispersant to prevent particle agglomeration. The three work together to adsorb gum, metal ions and free acid.

[0037] After hydrothermal modification with ammonia water, the Hβ zeolite forms a mesoporous structure (pore size 5 - 10 nm). Phosphotungstic acid is used as an acidic site to enhance the cracking activity. The two-stage process decomposes macromolecular resin acids through low-temperature pre-cracking (250 - 280 °C) and generates C10 - C20 hydrocarbons through high-temperature deep cracking (300 - 320 °C).

[0038] As an oxygen-containing component, polyoxymethylene dimethyl ether promotes complete combustion, and 2-ethylhexyl nitrate increases the cetane number; the ceramic membrane is resistant to high temperatures and corrosion, and the polyvinylidene fluoride membrane retains gums and catalyst particles, with a turbidity ≤ 0.5 NTU.

[0039] The technical solutions of the present invention are further illustrated below through examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0040] Example 1 Pretreatment: Filter the waste rosin oil through a 300-mesh filter to remove larger impurities, add composite adsorbent A (the mass ratio of activated clay, nano-silica, and sodium carboxymethylcellulose is 4:3:1), and the dosage is 20% of the mass of the waste rosin oil. Stir at 70 °C for 4 h and then filter.

[0041] Catalytic cracking: Mix the pretreatment product with catalyst B (the mass ratio of Hβ zeolite to phosphotungstic acid is 1:0.3), and the catalyst dosage is 10% of the mass of the pretreatment product. The reaction temperature in the first stage is 280 °C, the pressure is 0.5 MPa, and the duration is 5 h; in the second stage, the temperature is raised to 320 °C, the pressure is 0.8 MPa, and the duration is 7 h.

[0042] Refining: Add additive C (the mass ratio of polyoxymethylene dimethyl ether to 2-ethylhexyl nitrate is 4:1) to the cracking product, stir at 80 °C under nitrogen protection for 2 h, and filter in series through a ceramic membrane (operating pressure 0.6 MPa) and a polyvinylidene fluoride membrane.

[0043] Example 2 In this example, the same parts as in Example 1 will not be repeated, and the differences are as follows: Pretreatment: The dosage of composite adsorbent A is 5% of the mass of the waste rosin oil, and stir at 50 °C for 2 h.

[0044] Catalytic cracking: In catalyst B, the mass ratio of Hβ zeolite to phosphotungstic acid is 1:1.5, and the dosage is 1%. The reaction temperature in the first stage is 250 °C, the pressure is 0.2 MPa, and the duration is 2 h; in the second stage, the temperature is raised to 300 °C, the pressure is 0.5 MPa, and the duration is 2 h.

[0045] Refining: The mass ratio of additive C is 2:1, stir at 60 °C for 1 h, and the membrane filtration pressure is 0.3 MPa.

[0046] Example 3 In this example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Pretreatment: The dosage of composite adsorbent A is 12%, and it is stirred at 60 °C for 3 h.

[0047] Catalytic cracking: In catalyst B, the mass ratio of Hβ zeolite to phosphotungstic acid is 1:0.9, and the dosage is 5%. The reaction temperature in the first stage is 265 °C, the pressure is 0.3 MPa, and the duration is 3.5 h; in the second stage, the temperature is raised to 310 °C, the pressure is 0.6 MPa, and the duration is 4.5 h.

[0048] Refining: The mass ratio of additive C is 3:1, and it is stirred at 70 °C for 1.5 h, and the membrane filtration pressure is 0.45 MPa.

[0049] Comparative Example 1 In this comparative example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Traditional activated carbon adsorption is adopted (composite adsorbent A is not used).

[0050] Comparative Example 2 In this comparative example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Catalyst B only uses unmodified HZSM-5 zeolite and does not add phosphotungstic acid.

[0051] Comparative Example 3 In this comparative example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Additive C only contains polymethoxydimethylether and does not add 2-ethylhexyl nitrate.

[0052] Comparative Example 4 In this comparative example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Catalytic cracking is a single-stage reaction (temperature 320 °C, pressure 0.8 MPa, duration 12 h).

[0053] Comparative Example 5 In this comparative example, the same parts as those in Example 1 will not be described again, and the differences are as follows: Membrane filtration only uses ceramic membranes and does not connect polyvinylidene fluoride membranes in series.

[0054] Test Results and Detailed Analysis The products obtained from 3 examples and 5 comparative examples were analyzed and tested. The following 5 indicators were tested respectively: Impurity residue rate, test method: GB / T 511-2010 "Determination Method for Mechanical Impurities in Petroleum and Petroleum Products and Additives". Calorific value, test method: GB / T 384-1981 "Determination Method for Calorific Value of Petroleum Products". Catalyst life, test method: continuous reaction until the activity decreases. Sulfur content, test method: ultraviolet fluorescence method: SH / T 0689-2000 "Determination Method for Total Sulfur Content of Light Hydrocarbons, Engine Fuels and Other Petroleum Products". Storage stability, test method: visual stratification observation method.

[0055] Table 1 Analysis and Test Results

[0056] The test results are shown in Table 1. It can be seen from Table 1 that in Examples 1-3, the composite adsorbent A expands the layer spacing through acid modification (10% sulfuric acid treatment) of activated clay, and the specific surface area is increased to 200-250 m² / g. Nano-silica fills the pores, and sodium carboxymethylcellulose prevents particle agglomeration. The three work together to increase the adsorption efficiency by 3 times compared with traditional activated carbon, and the impurity residue rate is ≤2%. Comparative Example 1: The adsorption of traditional activated carbon only relies on physical adsorption. The particle size of 0.5-1 mm results in low pore utilization rate, and the impurity residue rate is as high as 12.5%.

[0057] In Example 1, two-stage cracking (low-temperature pre-cracking + high-temperature deep cracking) promotes the conversion of resin acid into C10-C20 hydrocarbons, with a proportion of ≥85%, and the calorific value is increased to 44.8 MJ / kg; the composite catalyst of phosphotungstic acid and Hβ zeolite promotes the decarboxylation reaction through the B acid site (3605 cm -1 infrared characteristic peak) and reduces coke formation. Comparative Example 4: Single-stage high-temperature cracking causes the volatilization of light components, and residual heavy tar (viscosity > 60 mm 2 / s) remains, and the calorific value is only 40.2 MJ / kg.

[0058] In Example 1, hydrothermally modified Hβ zeolite removes framework aluminum to form a mesoporous structure (pore diameter 5-10 nm). Phosphotungstic acid enhances the acid stability through the Keggin structure, and the catalyst life reaches 220 h. Comparative Example 2: The microporous structure (0.51-0.56 nm) of HZSM-5 zeolite is prone to carbon deposition and deactivation, and the life is only 55 h.

[0059] In the composite adsorbent A of Example 1, activated clay adsorbs sulfides (such as thiophenes) through ion exchange, and membrane filtration is used in series to remove sulfur-containing colloids, and the sulfur content is ≤50 ppm. Comparative Example 1: Metal ions (such as Fe 2+ ) are not removed, which catalyzes the formation of sulfides, and the sulfur content is as high as 215 ppm.

[0060] Example 1: In additive C, polymethoxydimethylethers (DMM3-8) reduce the surface tension of fuel, and 2-ethylhexyl nitrate inhibits oxidative condensation reaction. There is no stratification after 6 months of storage. Comparative Example 3: Lack of cetane improver, and oxidative condensation of phenolic substances leads to stratification.

[0061] In this application, through composite adsorption, two-stage catalytic cracking and additive compounding, waste rosin oil is efficiently converted into qualified biomass fuel, the cost of the catalyst is significantly reduced, the process energy consumption is greatly reduced, meeting the requirements of green production.

[0062] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing biomass fuel based on rosin waste oil, characterized in that: The method comprises the following steps: (1) Pretreatment: Filter the rosin waste oil with a 300-mesh filter to remove larger impurities, then add composite adsorbent A, stir at 50-70°C for 2-4 h, and filter to remove impurities; (2) Catalytic cracking: the product obtained in step (1) is mixed with catalyst B and reacted in two stages at 250-320°C and 0.2-0.8 MPa for a total time of 4-12 h; (3) Purification: Add additive C to the cracking product obtained in step (2), stir at 60-80°C under nitrogen protection for 1-2 h, and obtain biomass fuel after membrane filtration; The composite adsorbent A comprises activated clay, nano silicon dioxide and sodium carboxymethyl cellulose; The additive C includes polyoxymethylene dimethyl ether and 2-ethylhexyl nitrate.

2. The method for preparing biomass fuel based on rosin waste oil according to claim 1, characterized in that: The composite adsorbent A is prepared by compounding activated clay, nano silicon dioxide and sodium carboxymethyl cellulose in a mass ratio of 3-5:2-4:1, and the amount of the composite adsorbent A is 5-20% of the mass of the rosin waste oil.

3. The method for preparing biomass fuel based on rosin waste oil according to claim 2, characterized in that: The preparation method of the composite adsorbent A is: (a) The acid-modified activated clay and nano-silica were mixed, 5% polyvinyl alcohol solution was added according to the solid-liquid ratio of 1:2-4, and the mixture was ball-milled for 2 h at a speed of 300 rpm; (b) Add sodium carboxymethyl cellulose, spray dry at 60°C, and pass through a 300-mesh sieve.

4. The method for preparing biomass fuel based on rosin waste oil according to claim 2, characterized in that: The activated clay is acid-modified clay, and the specific steps and parameters are: immersing the clay in a 10% wt sulfuric acid solution, the mass ratio of the clay to the sulfuric acid solution is 1:4-6, stirring at 80°C for 2 hours, washing to neutrality and then drying.

5. The method for preparing biomass fuel based on rosin waste oil according to claim 1, characterized in that: The catalyst B is a complex of Hβ molecular sieve and phosphotungstic acid, the mass ratio of the Hβ molecular sieve to phosphotungstic acid is 1:0.3-1.5, and the amount of the catalyst B is 1-10% of the mass of the product obtained in step (1).

6. The method for preparing biomass fuel based on rosin waste oil according to claim 5, characterized in that: The Hβ molecular sieve needs to be hydrothermally modified before use. The specific steps of the modification are: placing the Hβ molecular sieve in a high-pressure reactor, adding 10%wt ammonia water, the mass ratio of the Hβ molecular sieve to ammonia water is 2-4:1, treating at 150°C for 6 hours, and centrifuging and drying.

7. The method for preparing biomass fuel based on rosin waste oil according to claim 1, characterized in that: In step (2), the first stage reaction temperature is 250-280°C, the pressure is 0.2-0.5 MPa, and the reaction time is 2-5 h; In the second stage, the temperature is raised to 300-320°C, the pressure is 0.5-0.8 MPa, and the duration is 2-7 h.

8. The method for preparing biomass fuel based on waste rosin oil according to claim 1, characterized in that: In the additive C, the mass ratio of polymethoxy dimethyl ether to 2-ethylhexyl nitrate is 2-4:

1.

9. The method for preparing biomass fuel based on waste rosin oil according to claim 8, characterized in that: The synthesis method of the additive C comprises the following steps: mixing polymethoxy dimethyl ether and 2-ethylhexyl nitrate to obtain a mixture, adding 0.4%-0.6% by mass of dibutyltin dilaurate to the mixture, reacting at 70° C. for 4 h, and removing unreacted substances by distillation to obtain the additive C.

10. The method for preparing biomass fuel based on waste rosin oil according to claim 1, characterized in that: In the step (3), the membrane filtration uses a ceramic membrane and a polyvinylidene fluoride membrane in series, and the operating pressure is 0.3-0.6 MPa.

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